She asks me for feedback
I wouldnt pussy foot about it too much.
She’s asked.
Tell her.
You can be polite, and you can have your critique pre bullet pointed so nothing gets dropped, but if she getts arsey about it you can remind her that she asked!
If you are concerned about your own welfare (which you reasonably could be) then request that another equal or more senior manager sits in, OR following the meeting agree that you will summarise by email and that you will copy it in to her an equal or more senior for completeness.
Keep good notes, just on the offchance (unlikely i would hope) that you need to do them for unfair dismissal in 6 months!
If she doesnt know, she cant act on it. While it might need to be handled quite formally, it can only be a positive thing overall.