libass https://github.com/libass/libass is an open-source library for decoding the .ass/.ssa subtitle formats for video files.

However, the automated censor-bot in the Google Play Store decided that an app supporting this format was violating the “Sexual Content and Profanity Policy”, and suspended it. The app was only reinstated after an appeal.

https://arstechnica.com/gadgets/2021/01/googles-bots-decide-ass-subtitle-support-is-too-risque-for-the-play-store/