OpenAI's auth seems broken on macOS' Firefox

I want to access ChatGPT from Firefox on macOS, but I can't pass the Cloudflare challenge.

I type my credentials, then get redirected to the Cloudflare page, pass the test, then get redirected again to https://chat.openai.com/auth/login, unconnected.

I tried to inspect the request but got nothing. I also tried to put a wrong password with exactly the same result.

The only solution I found was to connect from Safari and copy every session cookie from Safari to FF, which worked very well (to my biggest surprise! I thought modern session cookies would be tied to a browser?).

Anyone else having the same issue?