I have my phone since 2020, it has been working very well for the years that I had it until last April when I made a developer option go crazy and had to reset my phone because of that. Since that thing happened, my phone has suffered really weird glitches:

-It turns off by itself at any moment.
Sometimes I would just be sat watching a YouTube video or listening to music and my phone would just froze and the sound will loop like the last 0.1 seconds like a glitch sound somehow. And it’s happening like 2/3 times a day since April.

-The battery count sometimes stays at 100% for 10/20 minutes even with apps on.
This one is actually pretty recent and I have only experienced it a few times but it’s still pretty weird.

-The volume button is turning itself up.
Sometimes the volume when I’m trying to make it down SUDDENLY goes up and also when I have my finger on it (not pressing it, just having it close), the volume also goes up.

It came to a point today when while I was watching a video the screen froze and when I restarted it, I fell into the Recovery Mode. Having big traumatic experiences with that since April when I had to reset my phone, I want to ask what do I need to change. Is it a battery malfunction or the whole system is being fucking glitchy?