Multiple people have reported that you (and skeletons) can shoot arrows through blocks.
Related issues
Comments
CubeTheThird
migrated
We can kind of hit through the corner of a block, if the mob is close enough. Is that the case?
Torabi
Duplicate/related MC-3059?
migrated
Resolving as duplicate due to the lack of proper information.
Can you confirm this? How does one reproduce this? Please add more details.