The debuff timer for stun/paralyze effects is 1 second off. It displays every such effect 1 second too long which results in those wearing off at 1 second and not at 0 seconds as any other effect in the game. EDIT: Seems like it's the same for certain immunity and anti-CC effects.
Anything else seems to be working fine tho. Overall nice feature for people without timing-training, might make 1v1 more competitive.