Web app will not connect 'securely' in Firefox

Server Version#: 1.43.2.10687 (Linux native)
Player Version#: 4.159.0 (web app)

Cannot connect to the server using the web player (https://app.plex.tv/desktop/#!) in Firefox 151.0.1 (64-bit). Private browsing works. Chrome works. Desktop works. Apple TVs work. iPads work. Navigating to the local IP address works (192.168.50.148:32400/web).

Turned off all content blockers, both built-in and extensions. Still can’t figure out why it won’t connect. Any help deciphering what I’m doing wrong would be appreciated.

Perhaps Important note about the Plex Web app - Local Network Access