I considered replacing my profile picture, so I went to my settings and tried to upload a new one. At first it looked like it was working, but when I refreshed the page after clicking ‘Save’, nothing happened.
So I turned off my content blocking extensions, allowed Opera to permit trackers, advertisements, and protected content, and I retried to upload my profile picture.
Are you using a VPN or some other proxy? My first impression was that it may be related to file size, but the error message seems to indicate an "issue" with your public IP address
Have you been uploading (or attempting to upload) a lot, or did you get this error message on the first try? I know that something similar happened to me when I was uploading many images in a row
Are you also changing something other than your profile picture? This can happen if you try to save when the display name is too long, or if the bio is too long, etc. The problem is that if the saving fails for reasons like this, the UI doesn't tell you why which is a UI bug. If you know how to use dev tools in the browser, you can look in the Network tab why the PUT request for updating your account info is failing.