I’d click a number and it’ll immediately delete that number

Idk what’s going on with my iPhone XR I think it’s a defective phone like when I type in my pin on my lock screen often times I’d click a number and it’ll immediately delete that number and I would go to shut the phone off by clicking the power button and I’d type it in with no issue but let’s say I’m looking something up on the internet or I could be sending a text and it’ll scroll up aggressively then immediately drop down to the bottom of the convo or I could be on Snapchat watching the public stories it’ll exit out of the story and go back to that main page or it’ll just rapidly click through to the next post on that persons page until I exit out the page and when I go back it it’ll spazz out again what should I do?????