Please see this post in the main Affinity on Desktop forum for the original description.
When using the Haze Removal extension in Apple Photos to edit RAW and RAW + JPEG images, the display of the 'before' image is badly corrupted. In my case this is with Panasonic .rw2 images. The OP didn't specify what kind of images he was editing.
This occurs with the extension that is installed with Beta 1.10.0.244, hence my post here, but it's also present in the current Apple App Store version (1.9.3).
Cheers,
H