The bug

When a block is mined, it takes about five frames to update properly, which can be somewhat distracting.

slow.mp4

Here is a frame-by-frame analysis beginning with just before the block being broken:

Frame 0: Block is on last stage of the breaking animation. Next frame, it should break.

Frame 1: Pickaxe durability bar appears, indicating that the item was used. Block hitbox outline disappears, indicating the block is gone. The mining animation disappears. The block is still present.

Frame 2: No change.

Frame 3: Block disappears. No item is visible, breaking particles have not appeared.

Frame 4: No change.

Frame 5: Breaking particles appear.

Frame 6: Dropped item appears.

Expected behavior is for the block to disappear, and particles and items to appear all on the immediate frame after breaking the block.

Comparison
java.mp4