When the sandstone and red_sandstone block IDs were flattened, they lost their extra brightness applied to ambient lighting.

The following comparison screenshots (it's a GIF) were taken with an identical "Brightness" setting on both versions:

The intended brightness_gamma of 0.70 is still assigned in the 1.21.30 blocks.json: Changed to 1.0 in 1.21.60.22 preview

However, this assigned brightness_gamma is not used in-game due to MCPE-167836. Fixed in 1.21.60.22 preview

Expected Result

Sandstone and Red Sandstone blocks look the same before and after the Flattening.

Observed Result

Flattened Sandstone and Red Sandstone blocks look different than before, as their brightness_gamma values changed in 1.21.20, and have been intentionally set to 1.0 in 1.21.60.22 preview.