Keep in mind that the movie only wrapped filming earlier this year and then released the trailer soon after.
If anything, the only sin committed so far was not waiting longer to tease a movie that doesn’t come out until October.
While the teaser didn’t show him at all, that is probably due to the fact that the special effects weren’t finished in time for a trailer.
While fans worrying about the Venom movie is understandable given that Sony’s most recent attempt at Spider-Man had enough issues that they eventually let Marvel Studios take over, there’s no reason yet to go as far as to assume Venom isn’t in his own movie.