It is obvious in this game , that a character can not do 2 actions simultaneously - damage + buf or damage +debuff. It may seem like 1 action , but it always been 2 actions in a row - it was time when characters were first doing the damage and then doing the buff/debuff like Qui jumping on Savage with his dispell atack - first the hit was counted so savage gained offence, then qui dispel was counted and Qui removed offence. Then they "fixed"it for all characters - now they first apply the buff/debuff and do the damage afterwards. So now the situation is if Qui jump on savage, who have offence up already - first qui dispels the offence, then he do the damage and savage regains the offence. I would dare to say Fives was working as intended until today - he first did his debuff /speed down/ then he did his damage with basic atack and because it was damage on slowed enemy , it multiatacked .... They changed this again for Fives only ? So it is not bug fix , otherwise they should change again the "bug"when qui atacks savage who have offence and do not removes it .... it is intentional nerf of Fives only.
Cheers