Currently in the Curseforge App, Environment Tags only show if the File has been tagged by the Mod Author.
Environment Tags should show the Project's Default/Main Tags if none were selected for the specific file.

This would be very useful for modpack makers, as currently we have to manually go down the list of untagged mods to see if it's needed Server-Side since the Export Server Mods Filter will only select mods that have Server listed on their environment tags and ignore all untagged. While it wont fix the problem of completely untagged mods it will at least make the list smaller.