I wrote an mp3/ogg/flac/acc metadata parser over 10 years ago, and it was an absolute shower of shit with regards to character sets and compatibility between players and encoders. Has anything changed?
As others said, the only thing that changed is that most people stopped caring and moved on to streaming.
One thing that changed is that many users abandoned local audio files in favour of Spotify etc…
It's worse now, because there's more formats. Unfortunately, MP3 and AAC are still popular enough that software needs to support it, so you now need to support mp3/ogg/flac/aac plus opus, which is usually ogg container, but has its own additional metadata, and also sometimes it's in matroska container instead.