But that doesn’t explain how this iPhone is linked to another Apple I’d when I don’t have any other Apple ID and no one else has ever used this phone?
nevertheless, yr iPhone is linked to another device.
it is not probable that it a software glitch on apple's end.
that leaves only two possibilities.
1 your phone, after your purchase/acquisition of it has been used by some else else.
2 your phone was not unused/new before you purchased/acquired it. iPhones in seemingly factory wrapped packaging with setup screen appearing as first screen you see do not indicate a phone has not been used before.
i think you purchased this phone from an individual or store that trades in used iPhones.
the only recourse is to get the original user to disassociate the device from his/her account.
I can say with 100% certainly that no one else has used my my phone or at least not put their Apple ID into it...