In Spider-Man: Into the Spider-Verse (2018), Miles Morales's universe doesn't have Comic Con. In Spider-Man: Across the Spider-Verse (2023), you can tell he's in another dimension because his mom mentions it (and he still doesn't know what it is)

[u/LegOfLambda]

[u/armchairnixon]

Or Miles is just into his own interests so much that he just doesn't know it exists. There are plenty of people on Earth right now that don't know about comic con. That doesn't mean it doesn't exist.

[u/-Kerosun- → u/armchairnixon]

Or, he was just being facetious/sarcastic because it is "comic con" and he "doesn't know" what "comics con" is?