I started to have this on iPhone 8 right after 13.2.3 update and now every morning iPhone asks for Apple ID. this is happening because there is an option enabled to Auto update Apps overnight. What happens then is that the iOS is trying to run the update overnight and needs authentication; as it fails it pops up this message, there reason you are seeing in the morning is because you woke up just now and hopefully did not use your phone whilst asleep ;-) . If you test it, it happens roughly after midnight.
Find "App Store" app then press and hold and in new window click on "Updates" , you will then see that you have tons of Scheduled to be updated Apps. If you click update them all now , you will get that Apple ID request again.
Now the most confusing bit here for me is the fact that no other devices at home seem to have this, I have a newer iPhone at home (partner's) , this works OK, I also have my iPhone 7 from work -- this also works (all three have different Apple IDs) , also 3 iPads at home (all pretty ancient) and none ever requested this.
***Apple -- you should be more helpful here!
It would be interesting to see which models of iPhone are affected, and of course Apple should step in and help. I had a previously rather unsuccessful session with Apple support (a few months ago the same issue happened) and they advise to re-build the phone from new (no restore from iCloud), this worked till roughly about 13.2.3, and now it is back and drives me mad. I suspect this is a combination of specific Apple ID and their server settings and a bug in their iOS release. Internet is full of this, if you search, so this is not new.
Any thoughts would be welcome!