I have the same problem. Tried both Safari and Firefox on macOS.
I get this error in Safari's console upon clicking Generate:
SyntaxError: JSON Parse error: Unrecognized token '/'!
Screenshot 2022-12-30 at 19.53.00.png
I get this error in Firefox's console upon clicking Generate:
Uncaught SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data!
Screenshot 2022-12-30 at 19.55.03.png
I've inspected the JSON response and there was an offending / in the start of the response which makes it invalid:
/{"privkey":"...","pubkey":"...","was_clamped":true}