Destroying the block when it falls to the ground

Maybe "if not air at Y -1 do break block" on tick update? I have not made blocks with gravity before but try it and see if it works.

(My English is bad, I'm Chinese)

Try to create a Function and add it to the "TickFunction" tag, and write this in it:

execute at @e[type=minecraft:falling_block,nbt={BlockState:{Name: "you_mod_id:you_block_id"}}] run data merge entity @e[type=minecraft:falling_block,limit=1,sort=nearest,nbt={BlockState:{Name: "you_mod_id:you_block_id"}}] {BlockState:{Properties: {broken:true}}}

Please turn "you_mod_id:you_block_id" into yours.

Create a procedure, you just should let it place an air at where it is, assuming you name it "Broken".

Now you should modify you code of the block(so please make sure you don’t need to modify the basic properties of this block.)

and you should turn this code into you old code:

Please place the following code on the first line inside the first pair of {} after the first occurrence of the word "public" that you see.

    public static final BooleanProperty BROKEN = BooleanProperty.create("broken");

And now you can see many "import", please place the following code in their respective lines, regardless of the line number.

    import net.minecraft.world.level.block.state.properties.BooleanProperty;

    import net.minecraft.world.level.block.state.BlockState;

    import net.mcreator.                          .procedures.BrokenProcedure;

Fill in your mod id in the blank, without "_", and make sure to replace ‘Broken’ with the name you previously assigned.

Add the following code after the second-to-last "{" in the entire code block, and make sure to replace "Broken" with the name you previously assigned.

    @Override
    public void tick(BlockState blockstate, ServerLevel world, BlockPos pos, RandomSource random) {
        super.tick(blockstate, world, pos, random);
        int x = pos.getX();
        int y = pos.getY();
        int z = pos.getZ();
        
        if (blockstate.getValue(BROKEN)) {
            BrokenProcedure.execute(world, x, y, z);
        }
        
        world.scheduleTick(pos, this, 1);
    }

Now you block will broke when it land.