Combined PR's into optimized VCL file:
1. https://github.com/magento/magento2/pull/29360
2. https://github.com/magento/magento2/pull/28944
3. https://github.com/magento/magento2/pull/28894 
4. https://github.com/magento/magento2/pull/35228
5. https://github.com/magento/magento2/pull/36524
6. https://github.com/magento/magento2/pull/34323

@package magento/module-page-cache
@version 100.4.5
@level 0

diff --git etc/varnish6.vcl etc/varnish6.vcl
index 16dd950..468330c 100644
--- etc/varnish6.vcl
+++ etc/varnish6.vcl
@@ -10,7 +10,7 @@ backend default {
     .port = "/* {{ port }} */";
     .first_byte_timeout = 600s;
     .probe = {
-        .url = "/pub/health_check.php";
+        .url = "/health_check.php";
         .timeout = 2s;
         .interval = 5s;
         .window = 10;
@@ -81,24 +81,9 @@ sub vcl_recv {
     # collect all cookies
     std.collect(req.http.Cookie);
 
-    # Compression filter. See https://www.varnish-cache.org/trac/wiki/FAQ/Compression
-    if (req.http.Accept-Encoding) {
-        if (req.url ~ "\.(jpg|jpeg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf|flv)$") {
-            # No point in compressing these
-            unset req.http.Accept-Encoding;
-        } elsif (req.http.Accept-Encoding ~ "gzip") {
-            set req.http.Accept-Encoding = "gzip";
-        } elsif (req.http.Accept-Encoding ~ "deflate" && req.http.user-agent !~ "MSIE") {
-            set req.http.Accept-Encoding = "deflate";
-        } else {
-            # unknown algorithm
-            unset req.http.Accept-Encoding;
-        }
-    }
-
     # Remove all marketing get parameters to minimize the cache objects
-    if (req.url ~ "(\?|&)(gclid|cx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=") {
-        set req.url = regsuball(req.url, "(gclid|cx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=[-_A-z0-9+()%.]+&?", "");
+    if (req.url ~ "(\?|&)(gclid|cx|_kx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=") {
+        set req.url = regsuball(req.url, "(gclid|cx|_kx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=[-_A-z0-9+()%.]+&?", "");
         set req.url = regsub(req.url, "[?|&]+$", "");
     }
 
@@ -127,9 +112,8 @@ sub vcl_hash {
     }
 
     # To make sure http users don't see ssl warning
-    if (req.http./* {{ ssl_offloaded_header }} */) {
-        hash_data(req.http./* {{ ssl_offloaded_header }} */);
-    }
+    hash_data(req.http./* {{ ssl_offloaded_header }} */);
+
     /* {{ design_exceptions_code }} */
 
     if (req.url ~ "/graphql") {
@@ -147,13 +131,9 @@ sub process_graphql_headers {
         }
     }
 
-    if (req.http.Store) {
-        hash_data(req.http.Store);
-    }
+    hash_data(req.http.Store);
 
-    if (req.http.Content-Currency) {
-        hash_data(req.http.Content-Currency);
-    }
+    hash_data(req.http.Content-Currency);
 }
 
 sub vcl_backend_response {
@@ -173,9 +153,7 @@ sub vcl_backend_response {
     }
 
     # cache only successfully responses and 404s that are not marked as private
-    if (beresp.status != 200 &&
-            beresp.status != 404 &&
-            beresp.http.Cache-Control ~ "private") {
+    if ((beresp.status != 200 && beresp.status != 404) || beresp.http.Cache-Control ~ "private") {
         set beresp.uncacheable = true;
         set beresp.ttl = 86400s;
         return (deliver);
@@ -186,28 +164,18 @@ sub vcl_backend_response {
         unset beresp.http.set-cookie;
     }
 
-   # If page is not cacheable then bypass varnish for 2 minutes as Hit-For-Pass
-   if (beresp.ttl <= 0s ||
-       beresp.http.Surrogate-control ~ "no-store" ||
-       (!beresp.http.Surrogate-Control &&
-       beresp.http.Cache-Control ~ "no-cache|no-store") ||
-       beresp.http.Vary == "*") {
-        # Mark as Hit-For-Pass for the next 2 minutes
-        set beresp.ttl = 120s;
-        set beresp.uncacheable = true;
-   }
-
-   # If the cache key in the Magento response doesn't match the one that was sent in the request, don't cache under the request's key
-   if (bereq.url ~ "/graphql" && bereq.http.X-Magento-Cache-Id && bereq.http.X-Magento-Cache-Id != beresp.http.X-Magento-Cache-Id) {
-      set beresp.ttl = 0s;
-      set beresp.uncacheable = true;
-   }
-
-    return (deliver);
+    # If the cache key in the Magento response doesn't match the one that was sent in the request, don't cache under the request's key
+    if (bereq.url ~ "/graphql" && bereq.http.X-Magento-Cache-Id && bereq.http.X-Magento-Cache-Id != beresp.http.X-Magento-Cache-Id) {
+       set beresp.ttl = 120s;
+       set beresp.uncacheable = true;
+       return (deliver);
+    }
 }
 
 sub vcl_deliver {
-    if (resp.http.x-varnish ~ " ") {
+    if (obj.uncacheable) {
+        set resp.http.X-Magento-Cache-Debug = "UNCACHEABLE";
+    } else if (obj.hits) {
         set resp.http.X-Magento-Cache-Debug = "HIT";
         set resp.http.Grace = req.http.grace;
     } else {
 sub vcl_deliver {
-    if (resp.http.x-varnish ~ " ") {
+    if (obj.uncacheable) {
+        set resp.http.X-Magento-Cache-Debug = "UNCACHEABLE";
+    } else if (obj.hits) {
         set resp.http.X-Magento-Cache-Debug = "HIT";
         set resp.http.Grace = req.http.grace;
     } else {