I mean, to be fair, they have undercover people in any large demonstration, group, rally, etc.

They were in CHAZ/CHOP, in Minneapolis, in Kenosha. They're in the smaller rallies and groups lead by people who are trying to start a movement. They're in militias, big and small. They're certainly going to be in normal large gatherings requiring high security as well, like a political rally. (Especially if any chatter online may indicate to something else being planned)