Interaction with the left has taught me that both sides define kindness differently.

The right sees it in the traditional, conventional way. Being polite, offering to help, respecting life and boundaries, etc.

The left sees kindness on their own terms in order of their priorities, a kind of collective usefulness as they envision it. Making each other comfortable, donating to causes, standing in solidarity, even correcting each other. The flaw is that their position on being kind requires an antagonist to contrast. They tend to feed off of the position of whatever group they're seeing as virtuous rather than the context of a simple person to person encounter. They defer to the group for judgment on what virtue is, and they'll carry that with them.

This is why kind seeming little old ladies will still spit in your sandwich if they overhear you mention words they don't like, and they'll feel justified doing it.