iCloud photos locks my account for one hour due to maintenance

Hi, for the last few weeks I have been trying to declutter my icloud photos (I had reached about 83,000 photos and images). I download batches of maximum 1000 photos to my external hard disk and then I delete them from icloud. Unfortunately, I do get locked out of my icloud photos account again and again for one hour due to account maintenance. I could not find any reason why this is happening. How can I prevent this? All my devices are in the latest ios, they all have available space, and my PC (Windows, latest updates done) is working fine. Please help!!