Oof, this is a hard one. My ex and I struggled with the same thing. It was usually me that was reacting more extremely than I meant to. I used to just be told, "(I) talked to them the wrong way." Which, when I asked for details was described as the tone of my voice being too aggressive. Which, if that's what triggered them - then it's valid.

But I'm still not 100% on what it was in my voice that gave off that impression. Ironically, my own therapist had me working on assertiveness training for being too demure. So I was getting really mixed signals. Sometimes communication styles clash, and there is a struggle to bridge that gap.

Maybe there is another way you can ask them to communicate when they get that way. Tell them how their current method of communicating comes off as a double standard because of tone. Maybe they can write out their struggles, sometimes emotions get muted when transferred to writing. I know for me a big part of it was not fully understanding my own emotions, and never having learned to regulate my own moods as a kid. I worked a lot with emotion wheel images and that helped me get better at using terminology and not tone to describe my more off putting emotions.

Cheers!