There's no way to disable them in their mobile apps unfortunately without jumping through a couple hoops with something like a PiHole or using an alternative app on Android.
The alternative apps are great though. No ads, no tracking, included sponsorblock etc. I use libretube. Grayjay is also nice but a bit too commercial for me.
I don't use YouTube very often as I don't like the video format but sometimes I can't avoid it. And this makes it a lot more palatable.
I don't use YouTube very often as I don't like the video format but sometimes I can't avoid it. And this makes it a lot more palatable.