Just got a new phone (Pixel 10 Pro). Trade Republic gives me the same security message, so the app doesn't work. It still works on my Pixel 8. Same settings overall, I transferred everything to the 10 from the 8. Weird it still works on 8 (even no problem after uninstall / new install). No difference whether I install from Aurora or Play store.
The workaround didn't help in my case.
I now did the whole identity check thing and hope for the best.