My Brand new Ipad Air has been having bugs don’t know if it’s normal?

So i recently purchased a ipad air 4th gen. And for some reason the screen randomly dims to the lowest brightness even though it’s on 100% brightness. and i turned of dimming. And also for some

reason buffering is taking forever for youtube videos and it’s not my wifi connection because on my

old iphone it works super

fast. Don’t know if this new update has something to do with it.