I have the same problem. I have this for months now. It stopped after an update, but came back after another update.
I can’t use my sites anymore, I can only upgrade them or not use pictures.
Searching in the plugins is not possible anymore.
I use NGNX with let’s encrypt & I have the save all HTTPS option 2 chosen.
I have all my memory-shit together in the ini.php/ nginx.conf but I just can’t find the trick.
It is utterly frustrating.