simplyswords-fabric-1.56.0-1.20.1
fabric-api-0.92.2+1.20.1
Longsword of the Plague has a bug.
When the attacking player has the "Haste" buff, no matter how the opponent is attacked, it is impossible to convert all the buffs on them into debuffs. Once the "Haste" buff disappears, everything will return to normal.

@Sweenus