Lichess sound on firefox isn't working for me (even after following faq instructions to fix it).

Hi there!
I'm running firefox on a linux machine and recentenly, since a moth ago, the lichess sound stop to work on my web browser.

I've follow the faq instrunction (lichess.org/faq#autoplay) to enable autoplay, but it didn't fix the issue.

Could someone give me a sign of how I could fix it? please?