Why do earphones make my phone glitch?

hey! around 7 months ago i got a new phone (iphone 8). everything worked perfectly fine until around 2 months ago. basically each time i plug in my earphones my phone starts doing all sorts of weird things. the music turns on and off without me even entering the apple music app, i have to hold my phone at a certain angle for it to not do that meaning i have to always have it in my hand. it also makes my earphones make weird sounds. i tried changing them but it doesn’t seem to be helping. i’m planning on getting new original apple earphones but i’m scared that it’s just gonna be a waste of money because the glitching continues. has anyone had a similar situation and knows how to fix it or at least could tell me what caused this?