When dealing with children, the “oreo cookie” method works well - start with something nice, offer a “suggestion for improvement”, and then finish with something nice as well.

You’ll want to submit the politically correct version through official channels for traceability. After it’s submitted there, you can give a copy over slack. Don’t let anyone make any claims about what you supposedly said over slack dm. Leave a paper trail.

You’ve already been PIPed, so they have reason to look at you. Play nice and check the boxes; I would do the feedback even if the submission is entirely “yeah it was fine” level bs.

All of the above is playing it safe. Offer to provide additional feedback / “discussion” over a voice call as well, and ask what they’re looking for. If they’re building a case against your former manager, you can be honest.

If they just want “general” feedback, or they want it over text (“no time for a call”), or there are multiple people in the room, or the call is being recorded, then fall back to the politically correct version you already submitted.

Your nuclear button is to claim the PIP was retaliation for (something; you can make this up, just make it realistic), but you don’t press that button unless you’re about to be fired. It makes things extremely complicated.

I really hate office politics, but half of being promoted is knowing how to play this stupid game :(