I appreciate Google's transparency in their November 2020 Terms of Service update:
YouTube’s right to monetize. We’re gradually starting to serve ads on a limited set of brand-safe videos on channels not in the YouTube Partner Program or not under a monetizing agreement. There won’t be revenue share from these ads, but Creators can still apply for the YouTube Partner Program once they reach the eligibility criteria, which remain unchanged.
Ads are becoming increasingly ubiquitous, but I've found a workaround. Since the DMCA takedown against youtube-dl was dropped by GitHub, I'm putting more effort into a Plex library for my YouTube subscriptions. And just for clarity, I do support my YouTube subscriptions through Patreon, and I purchase all my Plex content legally.