I encountered this with Apple Music / Musicmatch. Tracks I'd ripped from original CDs were replaced with different recordings. Some were actually better, but

I encountered this with Apple Music / Musicmatch. Tracks I'd ripped from original CDs were replaced with different recordings. Some were actually better, but most weren't, and I kept running into region blocking on tracks I theoretically had ripped and held in my library (ie, I have CDs I bought when traveling to country AA, ripped them in the US, added them to iTunes, but when I turned on Apple Music and allowed my library to be "uploaded" or matched to the cloud I lost access to these tracks). I no longer subscribe to Apple Music and reverted to manually managing an mp3 library, or using Spotify (which definitely swaps tracks in and out of playlists).