Screensaver
This is a Big Sur iOS bug that Apple needs to fix, there is not a remedy posted yet, or an update with a fix. Big Sur iOS is ignoring photo edits, including cropping and rotation when photos are displayed on the screensaver
I think it is normal behaviour, since the Photo app keeps the original picture as the basis.
You should export your modified picture e.g. as a PNG file and use that as a screensaver.
