Well, this doc is from 2019, a lot of things can be changed.
As a linux user, there are a plenty software that can render it perfectly but cannot edit, and i really don't get it.
As a web developer i have to use photopea to be able to extract assets from psd files.
It's really strange that a web application can edit psd and a lot of powerful softwares like gimp and Krita have the exact problem with layers and masks with modern .psd files, so my guess its bcause photopea IT'S designed to be compatible with psd files.
I suspect it's incompatible by design with others softwares and not because it's has a poor specification.
If I remember correctly, PSD files have an optional header (when files are saved in "Compatibility Mode", which I think is the default) in which is encoded the rasterized image. It's then "easy" to display the image, but very difficult to edit it, as you then need to implement the whole renderer.
As a linux user, there are a plenty software that can render it perfectly but cannot edit, and i really don't get it. As a web developer i have to use photopea to be able to extract assets from psd files. It's really strange that a web application can edit psd and a lot of powerful softwares like gimp and Krita have the exact problem with layers and masks with modern .psd files, so my guess its bcause photopea IT'S designed to be compatible with psd files. I suspect it's incompatible by design with others softwares and not because it's has a poor specification.