I figured I would start livestreaming the development of this project on Twitch. I signed up as user pomThe, but it turned out pomthe:
https://www.twitch.tv/pomthe
If you are building user systems, you can have case-insensitivity under the hood but still display the username as the user desires.
Edit: Didn't realize livestreaming was one word.
Really liked Beam/Mixer's relatively cleaner interface, shame it was shut down. I think it might've supported the functionality you described.
The URL path itself seems to be case-insensitive.
I don't know what's the problem on your side.