Crashing/freezing apps, ongoing for years across different phones

I previously had an iPhone 8 and started to notice that, about 50% of the time when I switch back to an app that was already running in the background, it becomes totally unresponsive. It won't accept any inputs, remains stagnant on the screen for about 20 seconds and then crashes (disappears entirely - force quits itself).

This seems to happen most with: Reminders, Waze, Google Maps, WhatsApp, Chrome.

This never happens with: Calendar, Safari, Facebook, Instagram, AirBnB, Gmail, Youtube.

There are other apps where it happens and other apps where it doesn't happen, but I've just listed some of the most popular ones.

I thought it was a software issue so I did a DFU restore and then re-downloaded all apps individually and configured everything from scratch. No improvement.

Then I determined maybe the processor is just too slow to handle apps in 2020, so I upgraded and got a new iPhone SE 2020 (it has the processor of an iPhone 11) and I'm experiencing the same problem again. Except this time, if I wipe the phone, the problem goes away for about a month and then returns after the phone's seen some use.

Does anyone have any idea what could be causing this?