I think it's extremely important to recognize our inadequacies & to fully dedicate ourselves to improving on them, and to recognize the tendency to project those inadequacies onto other people.

Simple example:
Im 400lbs. I try really hard to believe i can be healthy while also being morbidly obese. I try really hard to believe im happy "just the way I am". But deep down inside, Im extremely insecure with how I look and how I feel.

Mister Christopher Johnson over there is lean, ripped, muscular and constsntly preaches his values of healthy eating, dicipline & exercise.

It triggers my semi-unconscious insecurity that I try so hard to cover up with "body-positivity".

So I leave bitter comments on his pictures telling him to "put your shirt onnnn". Or "ok mister conceited"

Or I comment on his posts about the importance of healthy behaviors saying things like "its unhealthy to care so much about how you look that you resitrict your food and hurt yourself with exercise" or "nutrition is great and all but it wont solve my type 2 diabetes" or "i tried nutrition and exercise one time, but it didnt work. Its psudoscience bullshit"

or "if i had good genetics i could do that too" or "where did you go to school to get your medical degree?" Or "yeah what ever. We're all gonna die one day anyway"

Blah blah blah, you get the point.
Of course there are many examples.
This is just the easiest one to throw out there on a whim.

Be honest about hoe you feel about yourself. Catch yourself when you feel the urge to dog at people. Ask yourself deeply and honestly if its coming from your own inadequacies. Maybe try telling yourself the exact criticism you're giving the other person and see if it matches up eith something you need to improve. Because ive found that 9 times outbof 10, my criticism towards others is generally me unconciously projecting my own criticism towards myself. (Although many times the criticism IS accurate for both parties)