Is this the intended behavior of Poppy's ultimate?

I played a game against Poppy earlier today, and the whole team found her incredibly frustrating to deal with.

Basically what she'd do: Fight you with her combo. "tap" her ultimate on you It'd make you untargetable and unable to control yourself for what felt like ages (although realistically it was probably 1.5 - 2 seconds) She'd proceed to kill you once you landed

Her gimmicky ultimate is cool and all. Her dash cancel is sufficiently frustrating on its own. But her ult being an instant cast aoe knock up (which is similar to a malphite ult in how fast it hits you, and seems to have a longer knock up) seems really OP / unfair. I mean, Malphite is really strong as a champion because of his ultimate and has a fairly weak kit otherwise to balance him out. Poppy gets a fairly strong kit, especially with the dash cancel effect, and on top of that gets a selective Malphite ult that can instead be channeled to knock an enemy out of a fight.

I think her ultimate should either: Scale damage as she charges it, so she can get the knockup but doesn't hit me for 200/300/400 + 90% AD when she instant casts it. The knockup does 0 damage and scales as she charges it over 3 seconds to full damage (the last second being extra so she can consistently get full damage if she wants).

or

The knockup should be removed as it's not as-advertised in her kit (she's not supposed to have a malphite ult in the previews of her, which is why it was so unexpected). Replace it with strictly the knockback, and make the time the champion is in the air scale with how far they're knocked back. If you want to insta-cast me with it, you only barely knock me off the ground.

Has anyone else seen her ult used this way? Those who have, do you think Poppys that use their ultimate as a knockup rather than a knockback are a lot stronger?