(iPhone 12 Pro, iOS 14.3) Asked to Update Apple ID Settings by Signing into Account that Is NOT Mine

I've had this problem on my old iPhone 6s as well. There is always a notification next to Settings, in which it wants me to update my Apple ID settings by signing in.

When I go to sign into my Apple ID, it asks me to sign into my dad's Apple ID. We used to share his Apple ID across our phones, but that is no longer the case, and hasn't been the case for years. We each now have our own Apple ID. Yet it still asks me to sign into his??

I keep digging around in the settings but it just wants me to sign into is account and not mine. I am signed into my ID on my phone, but for this it wants me to sign into his. It also gives me that prompt when I shut down and restart the phone, or once the phone is powered on again when it runs out of battery.

What can be done? Is there an easy solution to this? And no, I don't want to have to reset my phone to factory settings.