Half of my music is "currently not available in your country or region"

All was well until a few weeks ago half of my library become unplayable with the message "this song is currently not available in your country or region"

As far as I know I haven't changed any settings. I don't use apple music either and don't plan on it.

I've currently signed out of my apple ID on my laptop (windows) because it was also wanting to sync my library every time I connected my phone even if I just added a few songs and I read that this was a way to fix that.

The artwork for half the albums is also inaccurate (it seems to be mixing up artwork).

It should be noted that I've downloaded most of this music myself, because quite a lot of what I listen to isn't on apple music and I didn't want to have to worry about artists revoking the rights to their music through apple and stuff. Plus I support artists I like by buying their records and merchandise directly from their sites - I'd rather not support them indirectly through Apple. It's never been an issue until recently though.

All songs play fine on Itunes but the error appears when I attempt to play them on my Iphone.

Is apple automatically detecting downloaded music or something?

And why would certain songs be unavailable from the same album (as shown in the screenshot below)?

It's a very frustrating.

Any advice would be great.