Hi, large organisation with about 25 environments. Developers can see all environments in the designer, even if they don't have the Environment Maker role and up. That is, if they are only a Basic User for an environment, they see that environment in the Environment drop down in the Power Apps and Automate designer. Ideally they would only see environments for which they have the Maker role an up.
They can't build anything in the environments for which they are not Makers, but is messy. Ideally they would see only the environments for which they rights to build apps/flows in.
Also note that some can see, some cannot... as it turns out the sync to enable all users as Basic Users for unrestricted environments is not working as expected. Not related to this idea - but has been a source of confusion. We are forcing the sync via Powershell.