I say this as someone who considers themselves a leftist…
The lack of civility shown by left leaning people online is almost certainly pushing moderates into more extreme communities and the unhinged takes are perfect meme fodder for those with a bad agenda. Instead of channeling your anger at the person you’re corresponding with through your keyboard, channel it at a lack of empathy and understanding in society as a whole and respond with kindness and disengage when the conversation is not honest.
Repeat above for the use of “nazi”. The use of the word has become devalued because people like to fling it at folks with milquetoast centrist opinions, save it for people who are legitimately evil.