Yeah, it happened on one of my client sites. I also use shortcodes to insert standard classic menus in my templates, because, even though I really like the Block Editor and the FSE approach, one thing that totally doesn’t work for me is the menu paradigm there. Hence shortcodes to be able to use the good old menus (in precisely the way I want to use them). I figured out myself, that it must be the automatic update and downgraded the WP Version to fix it, but honestly: what a mess. Same learning from the issue like others here: no more automatic WP updates …