iCloud backup could not be completed

I have an iPhone 6s Plus, running IOS 14.2.

When I try to backup my iPhone to iCloud, it says “the last backup could not be completed”.

I’ve tried the the following:

I restarted my iPhone, I signed out and in from my Apple ID, I reseted my network settings, and nothing worked. I also have enough iCloud storage, and when I go to the “choose data to back up” settings, it shows that I have no data on my apps.

In addition, I keep getting a message in settings that tells me to update my Apple ID settings, and I’ve updated it but it comes back after a few minutes. It might have something to do with my problem.

Please help me solve this!

Thanks.