When editing a map, using the hotkey v for viewing as a player works just fine, but the same hotkey does not work for switching back to GM mode despite v being labeled as the hotkey for that too. Clicking it works as expected. FWIW, I’m running Firefox 105.0 on Linux.
Side note: I’ve been loving Shmeppy so far! Much easier to use than other digital tabletops 
Thank you for the bug report! I didn’t realize that hotkey was broken. I was able to prepare a fix for it, and it will be fixed on shmeppy.com once I deploy (which should be in the next couple days).
Took a bit longer than I thought it would to finish up the other work in this deploy (allowing games to be deleted) but just got it out today! The hotkey problem should now be fixed, let me know if you’re still seeing it though.
Just tested it out and it works, thanks for fixing it 