Android apps crashing in this manner may have been caused by having Google Play Services official package installed.
Going back to microG, apps are behaving mostly nice again.
EXCEPT for running native Browser for some reason causes all other apps to slow down to a crawl, major lag etc. As soon as I close Browser, everything becomes snappy again. What’s going on with this 
I do have 332 tabs open in Browser (so nice to just backup/restore across many years of phones), but as they’re just unloaded tabs, shouldn’t have any performance impact?
I’ve long wondered if Browser “live” card in app switcher is actually a real resource hog or not. But this problem definitely didn’t exhibit itself on XA2, so must be something else?