The all-pores mushroom block found in the Creative inventory (brown_mushroom_block with the huge_mushroom_bits value set to 0) inherits its drops from the regular brown mushroom block despite being a generic block and not explicitly a brown mushroom block.

This issue also affects the other unused all-pores states of both brown_mushroom_block and red_mushroom_block, but this report focuses on the all-pores block readily available through regular gameplay in Creative mode.

In practice, this means that the all-pores block:

• Drops 0-2 brown mushrooms instead of nothing when mined generically
• Drops 1 brown mushroom block instead of itself when mined with Silk Touch

In 1.21.20.21, this was fixed for mushroom stems (originally reported here), which inherited the small mushroom drops from the relative mushroom block ID despite being "generic" blocks and not specifically "brown" or "red".

Related issue: MCPE-76673 (all-pores block gives a brown mushroom block when pick-blocked)