Interesting! Feel free to join us during Office Hours today at 11am PST or next week (we are not hosting it this Thursday because of the holiday), we're happy to take a look at what could be causing this. If you can't make it, I'm also happy to continue helping you on this thread.
The next place to check is Branding settings:
We need to show the menu for end-users to be able to access the different environments:
If we have it hidden or "Powered by Retool" they won't have the option:
Note: This one is not clickable.