In the movies end credits tag, Venom is about to tell Eddie the history of the Symbiotes across time and the Multiverse, when there is a flash of light and they are teleported somewhere else. On the television screen in their new location, we see J Jonah Jameson revealing Peter Parker's identity to the world from the end of Far From Home and the Symbiote shows special interest when Peter's face appears on the screen.
The implication being that Venom was pulled into the MCU along with Alfred Molina's Doc Ock and the rest by Strange's spell.