I'm getting an error when I try to view this:
Secure Connection Failed
An error occurred during a connection to flatt.tech. SSL received a record that exceeded the maximum permissible length.
Error code: SSL_ERROR_RX_RECORD_TOO_LONG
No-one else?
Not even on my company's crappy proxy (not supporting QUIC and having problems with HTTP/2 sometimes). Works, loads rather quickly.
Works for me, no errors, using Firefox. But a quick peek at their Certificate Details shows several dozen Subject Alt Names.
That's probably a corner case which your browser's dev's failed to test.