Some Spider-Man: No Way Home concept art has surfaced and they include a couple of different gags involving Spider-Man wearing his Spidey suit inside out. One of those gags sees Peter Parker sporting literal underoos, while another suit design harkens back to an amusing moment in Spider-Man: Homecoming.
The concept art comes from Josh Nizzi and in the first one, after turning his suit inside out, Peter would have discovered that the underoos were likely placed there by Tony as a joke. The other piece of art shows the Spidey suit losing its stability and becoming baggy just like in Spider-Man: Homecoming.
Enjoy the concept art below!