Curious to hear what issues you faced (please!). I use FF (on Linux) as my main daily driver and I haven't had any issues with Causal (disclaimer, I work for Causal).

(granted, the experience is optimised for Chromium based browsers, but FF is not forgotten).

i registered before ok. now i can only see the alert on top to use chrome. no other content.

Works for me (Firefox on Linux).