iPhone glitch

So I’ve just recently bought an iPhone 12 Pro Max and only been using it for about 2-3 months it’s technically not been that long but still I’ve been experiencing my keyboard glitching when I type and whenever or when I watch recorded videos it glitches at first I thought it was their phone doing it but it’s not like when a video being sent to me by friends etc and I watch it it glitches but when I watch in apps like TikTok etc it’s fine and it didn’t happen before only started when I updated to iOS 15 so could it possibly be related to that or is my phone having problems cause I’d really hate that cause I just got this phone and haven’t done much with it besides playing games and watching movies