Have same issue on Realms, 1.19.30. I'd download the world but it's 300Mb+. Here is a screen shot. This is all over the map as well. New areas that have never been loaded, and current areas. Laying down a light block does not change the effect, and even the light block itself is blacked out. As you can see, my character is also a blacked out when in the middle of a dark area. If I quit the game session form there and go back in, the black area immediately where I am at will partially restore, but further out areas within view do not.
Downloading and running the world locally does not appear to have these shading issues. I did not travel thousands of blocks; however, the immediate area I am in on the Realm is affected by the bug.
No add-ons or texture packs enabled. I stopped playing, shut down Minecraft, and just came back and it's no longer happening.
I initially thought it was a texture pack, the Minecraft Update Texture pack, but I removed that and it kept rendering that way. I had applied that pack to see what it was about recently, and didn't see any difference and left it on. I got nothin'.