Something tells me that if we heard the other side of the story it might hit different. There's a lot of wiggle room in what "making his team members feel bad" could mean, and I would be surprised if constructively voiced criticism would have gotten someone written up.
With my experience of being written up for constructive criticism the reasoning was that I didn’t give constructive criticism to others and they felt singled out. I only give such criticism in private so of course they were not there to see the others. Apparently that wasn’t a sufficient explanation.
I've had it happen to me too, but my response was to resign on the spot (I was already not satisfied with the company).
The "toxic behaviour" I had done? I reverted a commit on the master branch that didn't compile, and sent a slack to the Dev who had committed it saying "hi! There appears to have been a mistake in your latest commit, could you please check it out and fix it? I've reverted it in the meantime since I need to deploy this other feature"
The dev responded by force pushing the code that did not compile to master and contacted HR.
I decided there was greener grass on other pastures. I was right.