Thanks for testing and reporting this! The QR endpoint itself works fine directly (POST /qr with {"text":"hello","format":"png"}), but sounds like the UI form may have an issue on mobile.

Can you tell me what happens – does the button just not respond, or do you get an error? I'll look into it now and push a fix if there's a mobile layout bug.

In the meantime, the raw API endpoint should work fine from any HTTP client.

Update: just pushed a fix that adds a loading indicator and visible error messages to the QR UI, so if it's failing silently that should now surface the error. Deployed ~2 min ago.

If you can reproduce it again and see an error message, I'd love to know what it says. Could be a rate limit hit, a CORS issue, or something else entirely.