What does the second post credits scene mean?
Finally, there is the post credits scene, after what seems like an endless list of super-talented computer effects artists that managed to make the preceding film look so nice. We're back in Scott's house in San Francisco and pan over a television that's on the Emergency Broadcast System, so we know we're in a world after the Thanos snap where infrastructure is in chaos (see Infinity War's post credits scene, helicopter crash and all). We move through the house, hearing some rhythmic clicks, until we settle on the giant-sized ant from earlier in the film, still stuck in Scott's routine, playing the electronic drums.
This shot was in the trailers for Ant-Man and the Wasp, and by the time the very end-of-credits comes along, you've probably forgotten that you saw the giant ant doing a lot of things in the movie, but not playing the drums. That was saved for the end… puzzlingly.