iphone stuck uploading to icloud photos

Hey,

I had the issue that my iPhone suddenly stopped uploading to iCloud photos a few month ago. It always said "Uploading 334 photos" ... and the number kept increasing the more pictures i took. I then turned off iCloud sync and turned it back on. Now it says "Uploading 51.722 Items" for weeks already.

I also check and tried the following (some of them again and again):

Phone is connected to power over night

Phone is connected to wifi over night

Phone is not in low power mode

Enough iCloud storage available (1.5T)

Restarted iPhone several times

Tried to pause and unpause upload

Turned iCloud photos off and on again

Tried to log off and log back into iCloud account

Tried "Optimise iPhone Storage" as well as "Download and Keep Originals"

I have the latest iOS Software on the iPhone 11 Pro Max.

But no change for weeks ...

It worked like a charm until it didn't. Please help! I also don't wanna lose the pictures that are not uploaded to iCloud yet.