@Gil44liG Sounds good. My fork is actually a bit of a mess right now, so I might be a while submitting this myself. If you do try it, feel free to do the PR instead. (Test code changes are pretty simple; let me know if you want them.)
@alanFlickGames I don’t think it would be specifically related. Thought experiments are failing me. 
A while ago, somebody mentioned to me experiencing capture-related issues on Windows, and wanting to give the aforementioned Vulkan backend a go. That ended up not having the problems. We suspected glReadPixels() being the culprit, but haven’t pursued it.
Maybe something like this is at fault. On Windows, for instance, external texture widths are finicky if you’re using the RGB format; I believe this needs to be generalized. (I wrote some workarounds in this regard for the Bytemap plugin, largely from guesswork since Solar wasn’t yet open-source, but since “it works” now, never got around to submitting a proper fix.)
I haven’t run into anything similar on Mac–I use captures rather sparingly, though–but maybe something has changed more recently, say with M1.