In general, appear and morph animations have to be super fast or else it gets frustrating because you can feel like the UI can't keep up with you. Disappear animations can be slower because you're never made to wait for something to close before you can do the next thing.

But maybe speed isn't the focus of this ticket? In terms of the actual easing curves used, whatever looks best is what we should choose I guess. :)

We should definitely define how the easing curves should look. Generally I think we should always use some kind of decelerating, but not accelerating, easing for appear animations and accelerating, but not decelerating, for disappear animations. We could look at Material design and specifically on how they are doing easing: https://material.io/design/motion/speed.html#easing.