A Spider-Man: Miles Morales player who's been searching for a glitch has certainly found one, and it'll give the player unlimited Venom powers. Check out the video from YouTuber Nobes, and read on for a break down.
Spider-Man: Miles Morales has some funny glitches that include floating carjackers and pedestrians slowly falling from the sky, but Nobes was specifically seeking out one that would "break the game" - and the one he finds is certainly capable of it. When entering the mission "Emergency Comms Down!" players are given a prompt to use Miles' bio-electricity powers to restore power to the emergency comms on top of a building.
Nobes realizes that every time they use a move, Miles' bioelectricity bar refills, so the glitcher tries to jump off the building and exit the mission. The game won't let you do that, however, without you completely abandoning it, so Nobes keeps using Miles' Venmo jump to get high enough in the Manhattan sky to exit the area entirely. Doing that will give you free rein throughout the Big Apple, with unlimited Venom power at your disposal. However, you won't be able to stop any crimes or start any new missions because you're technically still in one, so you'll be able to just faff about with your cool powers.
If you're in the mood, you can take a page out of Nobes' book and try and use your Venom jump to get as high as humanly possible - although that might take some time. In the video, Nobes claims they spent "three or so hours" boosting Miles up to around 250,000 meters - even though Miles disappears from view at about 16,000 meters. He makes it back down safely though, so don't fret.