<?php
/**
 * file: wp-content/plugins/gravityforms/includes/query/class-gf-query.php
 * lines: 331 - 333
 * Line 331: Here is where the bug starts, $value = [1, 2, 3], input type = 'number', and condition = 'in'. Despite $value being
 * an array, the conditions pass.
 * Line 332: The array is not numeric, so the condition passes
 * Line 333: The value is converted to a float (1.0) so the filter doesn't work
 */

if ( $field && $operator != GF_Query_Condition::LIKE && ( $field->get_input_type() == 'number' || rgar( $filter, 'is_numeric' ) ) ) {
  if ( ! is_numeric( $value ) ) {
    $value = floatval( $value );
...
// This is line 343, this never gets the chance to execute, but it should
if ( is_array( $value ) ) {

/**
 * file: my-code.php
 *
 * I don't think this is relevant, but this code is included in a GravityViews filter, which hooks into a gforms filter
 * executed in the file above (class-gf-query.php).
 */

...
$criteria['search_criteria']['field_filters'][] = ['key' => 1, 'operator' => 'in', 'value' => array(1, 2, 3)];
...
return $criteria;
...