Show Posts that are in BOTH Categories doesn’t work

Example Link attached (shows all Handcreams, not only vegan ones). From the WordPress Trac Core: https://core.trac.www.ads-software.com/ticket/55426

I use:
WPBruiser
301 Redirects Pro
Advanced Ads – PopUp and Layer Ads
Advanced Ads Pro
Advanced Ads – Sticky Ads
Advanced Ads – Tracking
Advanced Ads
Amazon Product In a Post
AnyComment
Code Snippets
Disable Admin Notices Individually
Disable/Remove Google Fonts
Easy Add Thumbnail
Easy Theme and Plugin Upgrades
Forminator Pro
GDPR Data Request Form
Glossary
Helpful
Stop Generating Unnecessary Thumbnails
MailPoet 3 Premium (New)
MailPoet 3 (New)
MyThemeShop Theme & Plugin Updater
Post SMTP
Real Cookie Banner
Schema & Structured Data for WP & AMP
Stop WP Emails Going to Spam
Advanced Editor Tools (previously TinyMCE Advanced)
TotalPoll – Lite
Two Factor
User Access Shortcodes
User Menus
White Label CMS
WP Force SSL
WP-PageNavi
WP Review Pro
WP Rocket
SEOPress
WP Statistics
Widget Disable

Theme: Divi 4.17.4

And the Code Snippets for my functions.php
https://drive.google.com/file/d/1sswH9DvdPGRvPlc_mfvWEGCv0moxvFyz/view?usp=sharing

Additional info: i’m Using WP 5.9.3, MariaDB 10.5 and PHP 7.4.

Error is also happening, when turning off all Plugins with WordPress’ Site Health Check.

The page I need help with: [log in to see the link]