I don't have a good ad blocker for you other than AdAway. It won't block YouTube ads on an unrooted phone, but it can on a rooted one. You can try in-browser mobile YouTube with Firefox + uBlock, but I would suggest switching away from the native YouTube app and getting NewPipe with SponsorBlock from F-Droid.
Highly recommended. You can even export your subscriptions from YouTube and import them into NewPipe. But that's for another thread. I use NewPipe almost exclusively now, having YouTube links pull up in NewPipe. No ads. And with SponsorBlock, you can skip the in-video ads (with community-driven data). Not to mention, you can also stream music from Bandcamp, and it supports PeerTube, etc, as well.
You need to add an Xposed module for it to block ads on YouTube though, requiring root. AdAway VPN mode on unrooted phones won't block YouTube ads. I just triple checked and tried it again to make sure I wasn't talking out of my ass.