Brave browser blocks most, if not all YouTube ads, one of the main reasons it's my default browser on iOS

Not with the YouTube app, but with the browser, you somewhat can.

I used adguard and it works for like 80 to 90% of the time. For the time where ad did show up, I just reload the page and it is gone.

A DNS based blocker like pi-hole, nextdns, etc, can't block YouTube ads. Or at least it's very hard to it without breaking something as YouTube often uses the same subdomain(s) to load ads and videos.

I use Adblock Plus on iPhone - can be downloaded in App Store and works fantastically with mobile Safari. I even replaced the Youtube app with a home screen bookmark and I haven’t seen an ad since

DNS-based adblock is mostly, but not totally, effective.