[GAMEPLAY] Vi gets displaced by Tristana ult while ulting.

I have only seen this once but I was able to get the replay and make a gif of it.

I think Vi is supposed to be immune to crowd control while dashing during her ult, and can then be knocked away once she has grabbed the target and knocked them up.

The issue here is if Tristana was able to ult before getting knocked up, it would have been directly in the path between her and Vi, meaning Vi should have been hit with it before arriving at Trist. Otherwise, it would indicate that the Trist ult had cast after being grabbed by Vi, which I didn't think would be something that could be cast during knock-ups.

I thought this is a bug, but I'm not sure what this would be classified as by the community.

Thanks