If I go to https://demo.jellyfin.org, after loging in with the demo account, no music or movie has sound.
The problem is not happining on Safari.
I tried disabling Content blocker and tracking prevention, even to authorise autoplay (although here I was clicking on play), but still no sound. Disabling extensions also didn't change it.
Other site with sounds like youtube or radio website are working correctly.
Interestingly the speaker icon is in the tab, so Orion thinks that sound is playing.
I use Orion Version 0.99.136-beta (WebKit 622.1.15.19.2)
on MacOS 15.6.1 (24G90), on a macbook M1 (13-inch, M1, 2020)

I see nothing special in the console.
I must say I find it particularly unnice that the link to this feedback website is not on this page:
https://help.kagi.com/orion/support-and-community/troubleshooting/bug-reporting.html
and that you have to create an account to report a bug.
sound is nice
0.99.136-beta
Sequoia (15)