Since iOS 13 : music app, mail app , search and settings crashing

Since the update to iOS 13 (on iPhone XS 256GB) I experience the following problems, even with the most recent update (13.3):

.) music app opens with a white screen and closes after ~10sec but stays in the background

.) mail app does the same occasionally, but usually doesn’t send/download mails

.) settings app freezes when scrolling down the list and closes after ~10sec but stays in the background, reopening gives me a white screen.

.) search doesn’t search immediately when typing and only finds apps if you type the full name, 50% of the time it even freezes

case is open since end of Nov.2019 (!).

backup/restore and factory defaults without restore done several times, three times at the Genius Bar, talked with countless senior support agents and spent 20+ hours with them.

Short (2min) and long (24hr) Logs have being pulled and sent over to the engineering team, but after 8+ business days no information about what they have done or if they have found anything nor what they plan to do next to find the root cause.

I‘m clueless what to do, especially because it looks like Apple support agents don’t care about cases that seem to impact only one person/device.