Why is iCloud backup saying the time remaining is over 12 hours?

My iPhone 12, which for 2 yrs has backed up to iCloud OK has started to say it can take up to 1 day to back up.

I have hardly any apps and has the smallest storage you can buy for the phone. It is updated to latest iOS, so

what is going on and how does this get fixed so I can back it up like before!

LordByron1960 wrote:

My latest attempt to backup my iPhone 12 Pro results in iCloud backup saying the estimated time is over 12 hours!

and it could be longer if this is your first time or it has been a long time since you've backed up.

tonight before, bed, connect to wifi, plug to power source, locked the device and leave it alone to back up.