Shulker bullets will not trigger a tripwire hook. I am not sure if this is affected in 1.16.4 as well, I did not have time to check. I have done testing in the snapshot and does not seem that it is affected.
MC-278639 Tripwire hooks are not activated by shulker bullets
MC-118441 Some entities do not directly activate tripwire and pressure plates
MC-92875 Collisionless blocks ignore entities with high velocity