Which Groupset?

Flexing the cranks to an extent that hinders performance? (you're racing, right?)

Which professional team are you riding for, and why don't you speak to your directeur sportif about it?

repped

Can still jump two sprockets on mine. Just push it further. No harder than doing it on my Shimano.

yeah - up 3, down 5 in one movement. If you're having problems it's for one or two of these reasons:

a) your cables need replacing
b) levers need servicing
c) you haven't got the derailleur cable set up right

That was my thought.

There's plenty of stuff that can flex between your foot and the power getting to the tarmac.

Play in pedal bearings.
lose crank arms.
lose crankring bolts.
worn freehub.
spokes.

To name a few. All of these would flex umpteen times more than a chainring, or crank arms.

I dunno, I def noticed more flex when I moved from the Spesh rings to TA on my S-Works cranks - probably felt it more keenly because I am heavy though