There is an unknown user on an unknown device a KD-43X8305C (Sony Bravia 4K TV) that seems to be able to change my songs at will. No one I know owns this TV either. I don't use Spotify Family, just student premium.
I've done all the normal guff, changed password, signed out everywhere, removed all old devices, checked for security breaches on my other devices, and even re-installed the app. The device is still there changing my songs randomly to things I've never heard of before.