iCloud Backup iPhone failing for over a year, no meaningful support from Apple

For longer than a year the iCloud backup for my iPhone is failing. I get a message "iPhone not backed up", then at the moment it says 4 weeks since last backup. Then I can go to Backup Settings or click OK. And in the Backup Settings all it turned on.

In the past it would work if I manually kicked off the backup, but this is also no longer the case. I also tried backup to iCloud via my MacBook, also will fail after a long while.

I have backed up a few times with my laptop, but it does not work for me in the long run. Also, I pay quite some money to have iCloud storage available. So it should work.

I have just chatted with Apple Support, and they keep suggesting to backup to my laptop as a solution. I was not getting an answer why they kept suggesting that instead of explaining what was going on.

I have 200GB of storage at iCloud in total, used 112GB at the moment. The amount of backup storage used is 10GB for this phone.

Now my iPhone 13 Pro Max 256GB is on 16.3.1, but it started on whatever version was out last year.

So, now my questions:

• Do I need to backup to my laptop and do a factory reinstall?
• When I put back the upgrade, will I have the same problem back?
• Or is there anything I could try to troubleshoot first?
• And how can I escalate stupid chats with Apple Support? (yes, I'm still steaming a little bit..)