Let's talk about Rek'sai's knockup
As it stands it is a fairly easy to land ability after using tunnel. And it is something that is easy to consistently land in both ganks and team fights.
The problem is that other champs have had their consistent non-ult knockups nerfed for being to reliable.
Take for example J4. He had his effective knockup area reduced. It was near impossible to get out of the area consistently without using flash and you only get to use flash once every 5 minutes meaning that repeat ganks on non mobile champs would usually result in a kill.
Not saying rek'sai needs a super small AoE for her knockup but the current area that is effected by the knockup is a fair amount bigger then her model size making it really easy to consistently land after using Tunnel.
Another option would be making the speed at which rek'sai moves when using tunnel. This would be in effect what was done to Leblanc's distortion recently to provide more counter play and it has actually really hurt Leblanc's overall power since there is a chance to react to it.
So riot before you consider nerfing Rek'sai's damage or base stats again please consider nerfing her reliable CC. Heck revert some of the stat changes and give us this nerf instead.