Captain Phasma's staff hits enemies even after she stopped swinging it.

If this is about she retaining the effect on her as she moves around, then refer to this report here: https://answers.ea.com/t5/Bug-Reports/Possible-to-create-a-lingering-damage-knockdown-hit-box-with/m-p/7591726/highlight/false#M21789

If this is about phasma's corpse retaining the staff strike effect, then this is the same as luke's and maul's and AFAIK doesn't have a proper report for it yet.