I think I know where in the code this could be happening for the web UI.
I’m not one of the devs but I’ll look into this a bit, I’ll update this comment when I get more info.
I believe !
should be changed to [!@]
in this line
https://github.com/LemmyNet/lemmy-ui/blob/129fb5b2f994e02bfecc36e3f6884bdbf485b87a/src/shared/config.ts#L47
And another elseif(match…) needs to be added for @ after this line
https://github.com/LemmyNet/lemmy-ui/blob/129fb5b2f994e02bfecc36e3f6884bdbf485b87a/src/shared/markdown.ts#L127
The bottom one is used to give more room when you sit down or need to get stuff from your pockets.