To use this script open your HumHub with admin rights and go to:

# Top menu -> Administration -> Settings -> Advanced -> Statistics

Inside the "HTML tracking code" copy paste this code :

<style>
    .thumbnail {
      	margin: 25px;
        box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19) !important;
        min-height: 300px;
    }
  	.img-profile-header-background {
        height: 100px!important;
    }
  	.profile-user-photo-container {
    	display: none;
    }
</style>
<script>
(() => {
    // Version 1.0.1
    const DEBUG = true;

    const _debug = (...args) => {
        if (DEBUG) console.log(...args);
    };

    const getId = (url) => {
        var id = undefined;
        url.split("&").every((element) => {
            if (element.indexOf("id=") === 0) {
                id = element.replace("id=", "");
                return false;
            }
            return true;
        });
        return id;
    };

    const setListTaskNumber = () => {
        // Add Task-%number% for every task in the list : /index.php?r=tasks%2Flist
        var elements = document.querySelectorAll(".task-list-item");
        if (elements) {
            var tasks = [].slice.call(elements);
            if (tasks && Array.isArray(tasks)) {
                tasks.forEach((element) => {
                    var id = element.getAttribute("data-task-id");
                    var detail = element.querySelector(".toggleTaskDetails");
                    if (detail && detail.innerText.indexOf("Task-") === -1) {
                        _debug("setListTaskNumber");
                        detail.innerHTML = ["<b>Task-", id, "</b> / ", detail.innerText].join("");
                    }
                });
            }
        }
    };

    const setListActivyTaskNumber = () => {
        // Add Task-%number% in the global tasks list : /index.php?r=tasks%2Fglobal
        var elements = document.querySelectorAll("div[data-task-url]");
        if (elements) {
            var tasks = [].slice.call(elements);
            if (tasks && Array.isArray(tasks)) {
                tasks.forEach((element) => {
                    var url = element.getAttribute("data-task-url");
                    if (url && url.indexOf("/index.php?r=tasks%2Ftask%2Fview&id=") > -1) {
                        var id = getId(url);
                        var heading = element.querySelector(".media-heading");
                        if (heading && heading.innerHTML.indexOf("<b>Task-") === -1) {
                            _debug("setListActivyTaskNumber");
                            heading.innerHTML = ["<b>Task-", id, "</b> / ", heading.innerText].join("");
                        }
                    }
                });
            }
        }
    };

    const setTaskNumberProgressionEdition = () => {
        // Add Task-%number% in detail of task : /index.php?r=tasks%2Ftask%2Fview&id
        var elements = document.querySelectorAll('button[data-action-click="task.changeState"]');
        if (elements) {
            var buttons = [].slice.call(elements);
            if (buttons && Array.isArray(buttons)) {
                buttons.forEach((element) => {
                    var url = element.getAttribute("data-action-click-url");
                    if (
                        url &&
                        (url.indexOf("/index.php?r=tasks%2Ftask%2Fproceed&id=") > -1 ||
                            url.indexOf("/index.php?r=tasks%2Ftask%2Frevert&id=") > -1)
                    ) {
                        var id = getId(url);
                        var text = document.querySelector(".task-head").querySelector("strong").childNodes[1];
                        var task = [" Task-", id, " / "].join("");
                        if (id && text && text.data.indexOf(task) === -1) {
                            _debug("setTaskNumberProgressionEdition");
                            text.data = [task, text.data].join("");
                        }
                    }
                });
            }
        }
    };

    const setTaskNumberActualityAndGlobalView = () => {
        // Add Task-%number% in the dashboard view : /index.php?r=dashboard%2Fdashboard
        var elements = document.querySelectorAll(".wall-entry-task");
        if (elements) {
            var tasks = [].slice.call(elements);
            if (tasks && Array.isArray(tasks)) {
                tasks.forEach((element) => {
                    var button = element.querySelector("a.btn");
                    if (button && button.href.indexOf("/index.php?r=tasks%2Ftask%2Fview&id=") > -1) {
                        var id = getId(button.href);
                        if (id) {
                            var body = element.parentNode.parentNode.parentNode;
                            var link = body.querySelector(".media-heading a");
                            var task = ["Task-", id, " / "].join("");
                            if (link && link.innerText.indexOf(task) === -1) {
                                _debug("setTaskNumbeDashboard");
                                link.innerText = [task, link.innerText].join("");
                            }
                        }
                    }
                });
            }
        }
    };

    const setFormTaskNumber = () => {
        // Add Task-%number% for every task forms (edition popup)
        var elements = document.querySelectorAll("form");
        if (elements) {
            var forms = [].slice.call(elements);
            var form = undefined;
            if (forms && Array.isArray(forms)) {
                forms.every((element) => {
                    if (
                        element &&
                        element.action &&
                        element.action.indexOf("/index.php?r=tasks%2Ftask%2Fedit&id=") > -1
                    ) {
                        form = element;
                        return false;
                    }
                    return true;
                });
                if (form) {
                    var id = getId(form.action);
                    if (id && form && !form.querySelector(".field-task-id")) {
                        _debug("setFormTaskNumber");
                        var titleField = form.querySelector(".field-task-title");
                        var body = titleField.parentNode;
                        var taskIdDiv = document.createElement("DIV");
                        taskIdDiv.setAttribute("class", "form-group field-task-id");
                        taskIdDiv.innerHTML = [
                            '<label class="control-label"><h4>Task number : #<b>',
                            id,
                            "</b></h4></label>",
                        ].join("");
                        body.prepend(taskIdDiv);
                    }
                }
            }
        }
    };

    const setMediaListTaskNumber = () => {
        // Add Task-%number% in the media-list block
        var elements = document.querySelectorAll(".media-list a");
        if (elements) {
            var links = [].slice.call(elements);
            if (links && Array.isArray(links)) {
                links.forEach((link) => {
                    if (
                        link &&
                        link.querySelector("strong") &&
                        link.href.indexOf("index.php?r=tasks%2Ftask%2Fview&id=") > -1
                    ) {
                        var id = getId(link.href);
                        var strong = link.querySelector("strong");
                        var task = ["Task-", id, " / "].join("");
                        if (id && strong && link.innerText.indexOf(task) === -1) {
                            strong.innerText = [task, strong.innerText].join("");
                        }
                    }
                });
            }
        }
    };

    const setAll = () => {
        setListTaskNumber();
        setListActivyTaskNumber();
        setTaskNumberActualityAndGlobalView();
        setTaskNumberProgressionEdition();
        setFormTaskNumber();
        setMediaListTaskNumber();
    };

    const delayedUpdate = () => {
        setTimeout(() => setAll(), 500);
        setTimeout(() => setAll(), 1000);
    };

    $(document).bind("click", () => delayedUpdate());

    $(window).on("popstate", () => delayedUpdate());

    delayedUpdate();
})();
</script>

Related to the product : https://www.humhub.com/en/
Tested version 1.14.3 / 15.09.2023