The damage of the wither boss skull shell is unstable (no projectile damage on direct hits)

Wither's projectile damage is unstable, sometimes it only damages one heart

repeat process
Summons a command block and turns it into purple and awaye-activates
and type /effect @e clear

observation results
Damage Winter has a glitch, sometimes it only comes in 1 damage (1 heart)

expected results
The wither projectile damage should deal the correct damage (4heart)