I don’t know what causes it, but I have footage from SU2 that shows the same behavior, so it is not new, same goes for transparent windows being seeing over the fog or the horizon being visible through mountains. Luckily all these things are not very noticeable in most flights.
These are some small graphical issues we need to live with, this is a computer software after all, maybe they will find a way to solve it in the future.