Hi,
I use Affinity Photo 1.8.5.703 on Windows 10 Pro 64bit version 2004
To reproduce the bug:
1) Open the file "alexandru-zdrobau-BGz8vO3pK8k-unsplash.afphoto" with Affinity Photo.
2) Double click in the layers pannel on the layer named "(Curve Adjustement)".
3) Close the "Curves" settings requester without change anything.
4) Uncheck the checkmark on the right of the layer named "(Curve Adjustament)"
Affinity Photo will crash
alexandru-zdrobau-BGz8vO3pK8k-unsplash.afphoto