It seems like Check Database is a necessary step to apply v3 scheduler into the collection (the popup disappears). The problem is coming back due to ankidroid still supporting V2, which may be fixed in 2.1.7, they will be using the same backend that removed V2
Don’t think it is add-ons because those that uses v2 scheduler should be broken in 23.10+
Removal of the v1/v2 schedulers
Code that imports from anki.sched will break, as the old schedulers have been removed. Typically you don’t need to do this unless you’re monkey patching the scheduler, which won’t work with v3. If you just need to call some scheduler method, you can do that via col.sched.foo()
Porting tips for Anki 23.10