Weird bug(?) with fish not responding to SIGKILL

bug.py

#!/usr/bin/env python3
import subprocess
from time import sleep
import sys

buggy = True

file = "'" + sys.argv[1] + "'"

p = subprocess.Popen(["fish" if buggy else "bash", "-c", "ffplay -nodisp -autoexit -hide_banner -loglevel error " + file])

sleep(5)
print(p.poll()) # None
sleep(0.5)
print(p.kill()) # None
sleep(0.5)
print(p.poll()) # -9
sleep(20)

# if buggy = True
# it keeps playing ...
# - if you Ctrl+C, it will stop
# - but if you let this script exit, it will continue

# I guess bash also lets it outlive the script?
# (that is, if you comment out the p.kill())
# idk what's going on lol