Backport PR #46567 on branch 1.4.x (BUG: groupby().rolling(freq) with monotonic dates within groups #46065 )
Backport PRs #46567, #46087

@mroeschke marked as draft as this PR also backports #46087 (which conflicts that caused the autobackport to fail)

The only conflict doing this was the release note in 1.5 (which would need a separate PR to move on main) (side note: why was the release note for #46567 in bug fix section and not regression?)

#46087 is labelled as an enhancement but could also be considered a bugfix? Although saying that, I think we generally don't consider changes to error message to be API changes (only changes to exception type)?

wdyt about backporting #46087? No pressure, but if you prefer not to, I will leave it to you to do the manual backport ! (you are more familiar with this code so less likely to make a mistake)
> why was the release note for https://github.com/pandas-dev/pandas/pull/46567 in bug fix section and not regression?

Ah sorry that was an oversight on my end. It should be in the regression section

> wdyt about backporting https://github.com/pandas-dev/pandas/pull/46087?

Sure, I'm ok with backporting since in essence it just changes the error message
 > > why was the release note for #46567 in bug fix section and not regression?
> 
> Ah sorry that was an oversight on my end. It should be in the regression section

no problem. will move it later (once the other note is synced up with main)