I've been a Firefox user for 15+ years. I love its flexibility, privacy, and (absent that rough patch in the mid 2010s) its speed. It really is a great browser. But I've hit a limitation.
One of my machines is an HTPC running Linux. I watch almost all my movies in the browser via streaming sites. At first, Firefox was ideal for this: it handles fullscreen browsing well (better than Brave) by letting me access tabs just by moving my mouse to the top of the screen. And I'm able to adjust the scale of the Firefox interface to make it more HTPC-friendly via about:config. That's not possible in Brave.
But Firefox has 2 issues that make it virtually unusable as an HTPC browser.
- When Firefox plays fullscreen video (on Linux), it can't stop the screensaver from coming on. This issue has sprung up repeatedly for over a decade and been reported multiple times.
- Extensions like Keep Awake/Caffeine do not work with Firefox on Linux. I use these extensions so that I can keep non-video sites (like Rollgator) on my TV screen persistently, without the screensaver coming on.
I'm bummed. I would rather use Firefox, with its great interface and its long history. I still use Firefox on my phone, laptop, and desktop. But at the moment, Brave is the only browser (of the two) that has addressed these issues on Linux. If that ever changes, I will happily come back to Firefox on my HTPC. (It would be great, because then I could easily send tabs from my devices to my TV!) Until then, I'm sticking with Brave.
I think that would be something related to your DE. In my case, I have the Plasma Integration plugin in both Firefox and Chromium-based browsers, allowing me to play videos full screen for long periods, the only nag being that if I have it full screen on one of my displays but there is any other window focused, it triggers the screensaver. For those cases, there are a few ways on KDE to prevent the displays to enter any saving mode with no more than 2 clicks, or a shortcut if you prefer to configure those