I use the voyager front end which lets me flare users. I believe you can also do this natively on the piefed default frontend (my instance is piefed). I’m not sure it’s possible on lemmy.

I've been here 2 years, and this is the first I'm hearing of this.

For you and @Lost_My_Mind@lemmy.world, if flair, in this case, is similar to tagging users in other clients, it's a setting and feature set of clients like Voyager. You can tag users by going to their profile, selecting the three dots or whatever to get things like block user, and selecting tag. You can even change the vote total for them if you enable the setting to track vote totals for accounts.

I personally only modify the votes for accounts that I negatively tag. A super negative total is dark red and stands out!