When the sandstone and red_sandstone block IDs were flattened, they lost their extra brightness applied to ambient lighting. This brightness is intended to be controlled by the brightness_gamma property in blocks.json, but since this property is not respected in-game (see MCPE-167836), the new IDs lost their special look.

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:

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

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, since they do not respect their assigned brightness_gamma of 0.70.

To Fix

Minecraft does not follow the brightness_gamma property from blocks.json, as described in MCPE-167836. This bug was briefly fixed in 1.20.60.22, but silently reverted, likely due to side effects described in MCPE-177356 (which are easy to fix). If these side effects were fixed and brightness_gamma was re-enabled, flattened Sandstone and Red Sandstone blocks would keep their original appearance.