Was playing around with falling blocks doing an hide-and-seek like command (execute at @a align xyz run summon falling_block ~.5 ~-.01 ~.5 {Time:-1,NoGravity:1,BlockState:{Name:grass_block}}), when I noticed that going on grass blocks with the vertical adjustment in the command (~-.01), has been replacing them with air, leaving above one falling block of mine (with Time NBT changed to 1). This occurs with blocks that have same id as BlockState.Name in my falling blocks; didn't try with special ones, like repeaters.