assassins breaking out of sniper freeze traps, bug? feature?

So i started to play sniper recently and have learned some better places to put freeze traps.
yesterday i had this assassin after me hardcore and with a vengeance.
Ive witnessed my freeze trap go off, freeze the assassin in place and immediatly the assassin breaks the ice with what looked like a smoke bomb?

is this some rare bug? or is it a feature?

I myself am familiar with this situation. And would like an explanation to why traps lock down isn't persistent.

Probably because Assassins can't take out the freeze traps like the other classes.

Probably because timing of getting caught in trap, doing smoke bomb = similar time to get caught in trap, wait to break free?

If the assassin lunges before the freeze trap strikes, they'll continue moving for the full length of the lunge even though there's ice on their feet. And if they're close enough, they'll still be able to grapple you while "frozen."

what I'm talking about is assassins after being frozen still literally breaking through half a second after being frozen still in ice, as if someone took a sledge hammer to the ice and shattered it.

i know its not the freeze effect expiring, cause it happened almost instantly after they were frozen still.

could one of their teammates have broken them free with an attack of some sort?

Perhaps a friendly sniper on the enemy team was looking out.

sounds like lvl1 or 2 traps im sure you can break out of both of those with lunge, charge, smoke etc