All third party apps are craching.

All of a sudden, all third party apps started crashing on my iPhone (iPhone Xs Max).

So what happened?

I was listening to some Spotify music and everything worked out fine. I paused as I walked the restroom and classic restroom behavior I decided to play some games on my phone. However... the game kept crashing at startup.

After that amazing restroom visit I tried to start Spotify again... but it kept crashing (remember I just used the app some minutes ago). I tried the game app, Strava, some Garmin apps and so on. And pretty much all apps I tried to start crashed (even those who were actually open since earlier).

So I restarted my phone. Sometimes the phone can behave strange and a restart my be necessary. But it did not work either. Still, all third party apps kept on crashing.

Here I realized that some apps that seem to crash were still open. E.g. if I open Strava it crashes at startup. But then when I look at "open apps", Strava is actually open. And then if I open Strava that way, it actually works (but it always seem to crash at startup). However, many apps do not work at all.

Any suggestions on how to solve this?

I actually uploaded a short screen capture here:

https://www.youtube.com/watch?v=OiX3OmR0kZ0&feature=youtu.be&fbclid=IwAR0vO0KGRgH54zXJ7b3p3vbD8cifHqV68QqrDEzSgc0USCODmtAf9txoOJs

Comment to the screen capture: The Garmin app actually worked when doing the screen capture. Also, Strava worked the second time I started the app from the actual "desktop". So the behavior isnt completely consistent. However, you do see the overall behavior of the apps crashing and some apps cannot be started at all...

The screen capture is made AFTER the restart of the phone. Also, I deleted the Spotify app and reinstalled it. This was also done before the screen capture, meaning that the problem remains.

Also worth mentioning: I only use 139,5 GB of 256 GB, so there's space available.