Slack no longer working in Iceweasel

I use Iceweasel (a libre/security-focused fork of Firefox). I use Parabola GNU/Linux and recently upgraded to Iceweasel version 108. Slack (a chat website) had worked with the previous version I had installed; however, now Slack does not seem to work. It gives me a page saying that my browser is no longer supported, despite the system requirements saying that it supports Firefox v.92 or above. Does anyone know what has changed here? Is there any simple way to resolve this issue, so that I can continue using Slack with Iceweasel?