Downloaded music not playing on iTunes library on iPhone

My entire itunes library consists of music I've downloaded onto my PC, no files from apple music or any other music streaming websites. Previously, all music I've downloaded and selected for my iPhone were able to play just fine, prior to 2022. However, some songs are greyed out, with the error message "This song is not currently available in your country or region". This seems to be at random, as every time I sync my phone to my computer, different songs are greyed out. All songs are playable on iTunes on my PC, and I have about 130gb of free space on my iPhone, so it's not like disk space is the issue.