Because he still relies on what he perceives at the moment to change the future. And thus his reflexes, this was shown by his inability to react in time to Ichigo blasting him with a Getsuga or the arrow shooting him from the back.
What do you mean "what he perceives at the moment"?
So much context ignored in this post;
- Aizen was fucking with Yhwach's visions of the future which allowed most of that to transpire.
- The silver arrow is a deus ex machina that nullifies all of Yhwach's powers
Neither of this applies to Midora at all.
Yhwach can see all futures even distantly into them = Midora is never tagging him.
Yhwach can manipulate the future freely even undoing his death = Midoria is never tagging him let alone putting him down.
Food Luck passive prevents that from happening
Food luck is fodder in general, nevermind when compared to the power to change the literal future.
or Yhwach just becomes Midora’s shortlived punching bag once he can’t revive. Which doesn’t take much based on the limited number of times he could revive or how the Soul King went out
Source for Yhwach's ability to rewrite the future and undo his death being only achievable a limited number of times?