Peter Parker is not having a good time. Five years ago, the No Way Home ending erased him from the memories of his loved ones, leaving him completely isolated. Fast forward to Spider-Man: Brand New Day, and Spidey is still all on his lonesome, burned out, and operating from a run-down apartment.
It's so bad, in fact, that Peter's own body betrays him: his arachnid DNA begins to overwhelm him, transforming his powers in ways he can't control. His helpful AI assistant EV warns him that his illness is a consequence of unresolved trauma, but still Peter doesn't stop. Instead, he decides to build a device that will restrict his powers.