Wither effect from wither boss lasts way too long

When fighting the wither, and a player in survival mode gets hit with one of the wither's skulls, the player will receive 40 seconds of the effect wither 2, instead of the intended 10 seconds. (This bug only happens in hard difficulty and works as intended in normal difficulty.)

How to reproduce:

1 - Spawn a wither (/summon wither) or build the usual structure to spawn one (4 Soul sand in a T shape with 3 wither skeleton skulls on top)

2 - go into survival mode, if not already. (/gamemode s, or go o settings > personal game mode > select survival)

3 - Once the wither has spawned, get hit by one of the wither's skulls, and the result should be that the player receives 40 seconds of the wither 2 effect rather than 10 seconds. (In hard difficulty)