As many know, the rights to certain Marvel film properties are not owned by Disney, but by Sony Pictures. In particular, this includes the characters of Spider-Man and Venom. Now, we all know that Spider-Man is currently part of the MCU under special agreement between Sony and Disney.
Yet it is claimed that Venom is not. In particular,
There's no mention any other part of the MCU in Venom (2018). And I've seen the argument on Youtube that the lines between Brock and Skirth in Venom stating that for there to be aliens is "completely crazy" means it can't possibly be the MCU since alien interference on Earth is very much public knowledge in the MCU (The Battles of New York and Wakanda, Thor, etc.)
On the other hand:
The title cards on Venom state that it is "in association with Marvel" and there is a cameo by Stan Lee, which is very much in keeping with MCU films.