Did some research but looks like one other report has this issue in an older version (1.16.1 or so...) of bedrock pocket edition.

Yesterday the lighting on my world's Nether was ok with brightness all the way up. Today is seems like the settings are on moody with the brightness all the way up. In the debug I believe it is telling me that the shadows are really high. 

There is a Piglin Bastion across the lava lake in the one screenshot that is no longer visible with this lighting bug. There has been no windows update installed either. The only thing that I have done that might warrant a lighting bug is I finished a cylindrical smooth stone slab roof over my Zombie Piglin farm at the nether build height, but the farm is not in loaded chunks in these screenshots.