"Song not currently available in your country or region" after ios 16.3 update

I've started getting a "This song is not currently available in your country or region" error on my iPhone 12 mini after updating to ios 16.3. The songs in question should be uploaded since I sync my entire music library, are not uploaded to the phone, but they show up as greyed out in playlists.

These are my MP3s, which all play in iTunes on my Win10 system and on my Touch. All OSs and apps are current and up-to-date. I have NEVER run Apple Music so supposedly streaming/song matching should not be an issue.

What is there to be done?