Slay and serve are part of the drag/queer community lexicon that were made popular (iirc) in the NY ballroom scene. No one cares when 6th graders use them or if they stop.
If you watch queer media or hang out with The Gays, you’ll hear them all the time. They’re a bit campy, but not cringe.
The issue is that that’s who Biden and leading members of the democrats are. They do not, in my opinion, have the framework to deal with a political campaign being an existential threat.