Not getting that here, did you have some custom shader enabled? Transparent floor is a shader option that was added with last atmospheres update to allow atmos objects go below floor level and still be displayed, what you have there looks exactly like it.
Fixed
What's the script you're running, something third party?
Not getting that here with that resolution, not sure how I can replicate it. We've been getting reports of it across different versions but that seems to be hardware dependent and thus only affecting a (small) portion of people.
Will look into it but no guarantee it'd be included with this update. Not sure why it broke again, I don't think we changed it with 5.43.
Linux build is now also available on Steam, macOS will come with stable release.