Phone Keeps crashing, WIFI & Bluetooth refuse to work but a diagnostic test says everything’s fine?

So my iPhone 12 Pro is acting weird; this has been happening for about three months.

Essentially, the phone freezes at random then shuts down (crashes) and I have to manually turn it on again. When I do this I have to turn on the WiFi and Bluetooth manually as well but lately they both refuse to turn back on.

Then it proceeds to be as slow as possible and sometimes refuses to do anything (phone calls, texts, etc) It even doesn’t work if I turn it off myself to restart it. I’ve already tried resetting it, didn’t work.

I finally had enough yesterday and I got it checked out with a tech team. When they ran a diagnostic test they saw absolutely nothing wrong with it. I just want to fix this thing.