WordPress 5.4 and higher: Filter posts by category 1 AND category 2 in API requests

Related Posts:

1. Is There a Difference Between Taxonomies and Categories?
2. Check if a post is in any child category of a parent category
3. How to export and import taxonomies (category, tag and/or custom taxonomy) and their terms
4. How to display non-hierarchical taxonomy as terms with checkboxes?
5. get_categories for custom post type with a specific custom taxonomy attached
6. Control term order on a per-post basis
7. Could not insert term into the database
8. How can I add the featured image functionality to a custom taxonomy?
9. Share one taxonomy across multiple blogs in 3.0 [duplicate]
10. Can a Child Category Have More than One Parent?
11. Combine two taxonomies in a hierarchical tree
12. Weird behaviour when adding terms/term_taxonomies programmatically
13. How can I select a primary category?
14. wp_update_nav_menu_item() to insert categories
15. Admin Panel – Disable Moving Selected Terms To Top of Metabox
16. How to make custom taxonomy check boxes like ‘Categories’
17. Create terms when registering taxonomy?
18. How to create non-unique sub-category slugs?
19. How to get next previous category in same taxonomy?
20. Display only deepest category on a single post?
21. How to add HTML5 ‘required’ attribute to wp_dropdown_categories() without JavaScripts?
22. How to Override default update_count_callback for category
23. Wrap a chosen category name with div
24. Does WordPress Offer a Way to Find All of the Categories that Don’t Have Children?
25. Add custom taxonomy terms to WordPress menu dynamically & append #slug to url
26. wp_list_categories, Add class to all list items with children
27. Getting WordPress custom taxonomy/category?
28. Display empty taxonomy terms with get_terms()
29. Return category slug / title from category ID
30. Connecting WordPress gallery to custom categories (taxonomy)
31. How to get the number of child categories a specific parent category has?
32. Get term by slug in Gutenberg
33. What’s the difference between “parent” and “category_parent” in a WP_Term object?
34. Update taxonomy value of post type in query
35. How to query posts from specific authors and categories using WP_query?
36. How to get the depth of a category’s subcategories
37. New categories are now going to 404s
38. How can I convert some categories to a custom taxonomy?
39. Any way to assign Post Categories and Tags to Links?
40. Add custom taxonomy under the category title
41. Display name of the last child category
42. Best way to programmatically link to multiple categories (union/intersection) [closed]
43. “Reversable” and “Re-useable” Subcategories (or other taxonomic structure)
44. Get multidimensional array that reflects category hierarchy
45. Want to hide some categories from the categories meta box in the post editor for the two specific user roles
46. How to export/import categories and keep their IDs?
47. How to use wp_category_checklist()?
48. List Terms in Category
49. How to get category URL with the slug?
50. Get all sub-categories of a parent category
51. Can I use get_adjacent_post for specific categories?
52. How to view WordPress’ default category IDs?
53. Random taxonomy category list
54. Taxonomy filter all children
55. Display Slug instead of Name
56. Force a user’s posts category
57. Search Posts / Pages with multiple options?
58. Change existing taxonomy settings when using custom taxonomy
59. ACF: Display category name using taxonomy field
60. How to get the id from the custom category?
61. Show Available Taxonomy List with Current Category
62. category filter doesn’t work in WPML
63. How to filter out Categories for specific post types on WordPress Admin?
64. Exclude a category from the_category in the single post page
65. How can i insert term in a specific language of Polylang?
66. Taxonomy name repeating when showing 2 posts from each category
67. Why does the argument list_only do on Walker_Category_Checklist::start_el?
68. New Categories Not Shown In the Post Edit Page
69. How to add a post with new Taxonomy without assigning to default category?
70. Grouping parent categories into sections
71. get_adjacent_post_link excluded_terms ignored
72. Match two taxonomies to display a specific content
73. Taxonomy for custom post type not found
74. Category base 404 – fix
75. Why is my post categories not displaying?
76. Display only the latest post
77. Problem importing categories and sub-categories
78. Return selected categories only in custom page meta box?
79. Assign a category by user and customize the edit-tags.php?taxonomy=category page
80. list taxonomy based on taxonomy
81. get IDs from links categories
82. Multiple Parent Category URLs
83. Chained drop-down menu for custom taxonomy using chained.js
84. Show parent-child relationship for categories in the wordpress admin
85. Display only one level subcategory in wordpress
86. Converting Categories (with ACF fields) to custom taxonomies
87. Woocommerce custom taxonomy order
88. Hook action when create new category [duplicate]
89. Taxonomy term RestApi data 10 rows limitions
90. Order Categories by Character Count
91. Images as Categories
92. hide_empty property not working when using get_terms
93. Add custom fields to Woocommerce Category Page
94. Quick Edit on taxonomy names results in error
95. How to make /category/ URL load properly instead of 404 error?
96. How to get parent and child sub category (Taxonomy) order to display
97. How can I get the categories and subcategories separately?
98. When using get_terms with hide_empty = true, terms that only contain scheduled posts are not returned. How to override this?
99. Two related taxonomies. how to filter terms in second taxonomy depending on selected term in first taxonomy on Post edit page?
100. get_term returns different results, sometimes empty, sometime the correct list