https://arstechnica.com/gadgets/2022/03/google-shuts-down-youtube-vanced-a-popular-ad-blocking-android-app/

YouTube Vanced, a popular mod of the official YouTube Android app, is dead. The project announced its discontinuation over the weekend. The project leaders are being weirdly coy about why the app is shutting down, but The Verge confirmed that a cease-and-desist letter from Google is the reason.

YouTube Vanced, which was created in 2017, is a mod of Google's Android YouTube app. The developers decompiled Google's official YouTube app, added additional features, and distributed the resulting code. The primary appeal of Vanced was the ad-blocking feature (the name is YouTube "AdVanced," but without the "ad"—get it?) and background playback. Along with the copyright infringement of redistributing Google's proprietary code and infringement of the YouTube trademark, you could consider Vanced a form of piracy since it was essentially a cracked version of the YouTube app that enabled most of the $12-per-month YouTube Premium features for free.