iPhone won't backup to iCloud even though plenty of storage

I have an iPhone SE 2020. I continually have the red icon in settings that indicates a message. It says my iPhone can't be backed up because my iCloud storage is full. But that's not the case. When I go into iCloud on my phone in Settings, it says I am using 225.1 MB of 5GB. That's because I've turned off most large things, such as photos, messages, etc. so that it isn't trying to backup those large data items. I never back up my photos to the cloud anyway. So I can't figure out why it won't back up my phone. Any ideas? I'm on IOS 16.2. This has been an issue for months - maybe even a couple of years. I don't think it has ever backed up since I got the phone (I didn't buy in when it came out in 2020, but rather bought it used probably sometime last year). I've researched it before and not found any solutions, so I just kind of let it go. But I finally figured I'd ask on here for help. I can back up to my laptop via iTunes, but not to iCloud.