All incoming calls display same CID # and location

For the last month, every incoming call I receive on my iPhone 8 shows the same phone number/location (Wisconsin) on caller ID. My recent calls never show the number though. This makes it appear every incoming call is spam; I answer only if I’m expecting a call. I’ve tried rebooting multiple times and the problem never improved and certainly didn’t resolve.

And yes, I know it’s an older model device but it worked just fine until now. The Apple store and my carrier were equally unhelpful as both pointed the finger at the other. I don’t care who’s at fault; I just want it fixed so don’t have to play a cell phone version Russian roulette.