[Regression 6.8.2->6.8.3] Android apps hang with black screen or splash screen

in Qt Creator, go to examples, select "Coffee machine". Select Android+6.8.3, configure and build it. (or 6.9.0)

Tested on multiple android phones, sdk level 34 for the build, but tested on both Android 14 and 15 phones.

The hang happens more or less randomly, HOWEVER:

To reproduce it every time:

(1) go to developer options and select "Don't keep activities" and "background process limit: no background processes"

(2) start the coffee machine app. it works fine.

(3) put it in the background

(4) bring it back, it hangs at a black screen. you might have to give a couple of tries to get it to hang, but it always hangs.

This bug didn't exist in 6.8.2. The bug happens often enough to render 6.8.3/6.9.0 nearly unusable for android apps.