Does Firefox work without the VPN?

If it does, you should direct your question to PIA. https://helpdesk.privateinternetaccess.com/

I have had the exact same issues as the OP, and as they stated, the issues only occur when using Firefox. It does not happen when using Safari, but just like the OP, I prefer to use Firefox rather than Safari. This problem has been happening for a very long time, I can't say exactly when it started, but one day all was well, got an update from Firefox, it installed as usual, then my PIA VPN stopped working on several sites. Since PIA VPN does tend to work when using another browser, them I would suggest that your suggestion to take up the issue with PIA would not be the way to go about resolving the issue. Either Mozilla fixes its issues with Firefox not working with PIA's VPN, which had been working flawlessly, in the past, or I switch to a browser that will allow me to use a service for which I am paying, without restriction. I have used Firefox for many many years, and would not like to stop using it, it's a great browser, but I will stop using it if the problem is not resolved, and soon. I have put up with this for far too long without having said anything, and that stops today.

Firefox stopped working with my VPN on when I updated my OS to Sonoma, yesterday. I use PIA for my VPN. Finally, I turned off my VPN and, viola, all sites work. Turned it back on, and can’t navigate, again. For instance, I tried to open YouTube, and got a blank screen. Turned off VPN, and got to main YouTube page. Turned the VPN on and tried to log in…nope. Turned it off and logged in. Turned it back on and tried to open a video….nope. Turned it off and opened the video…etc., etc..

Even though you clearly demonstrate here that the issue is the VPN service, you still think Firefox needs to fix it. I find your logic interesting.... Did you even open a service request with PIA since you're paying for it?

Found this on reddit and users have the same issue -->> https://www.reddit.com/r/PrivateInternetAccess/comments/17cb7rc/pia_firefox_many_sites_wont_load_and_wont_even_go/?rdt=38503

https://www.reddit.com/r/Express_VPN/comments/pp6lwf/former_malware_distributor_kape_technologies_now/

Not sales, but try Mozilla VPN and see if you have the same issue as a test. Is there a part of the vpn app that shows logs to see what is being blocked?

Just a little research into PIA shows that the current CEO was part of that Mt. GOX bitcoin issue years ago... https://en.wikipedia.org/wiki/Private_Internet_Access https://en.wikipedia.org/wiki/Mt._Gox

On November 18, 2019, Private Internet Access announced that it would be merged into Kape Technologies, which operates three competing VPN services, CyberGhost, ExpressVPN and Zenmate.[9] Some users objected to the acquisition, as Kape (under its former name, Crossrider) previously developed browser toolbars bundled with potentially unwanted programs.

Red flag for me... It's based in the U.K. (specifically on the Isle of Man) and owned by an Israel-born Cypriot investor

<<Even though you clearly demonstrate here that the issue is the VPN service, you still think Firefox needs to fix it. I find your logic interesting.... Did you even open a service request with PIA since you're paying for it?>>

I did not think that Firefox needs to fix anything, I was simply asking a question. Casting aspersions on my logic or lack thereof is a bit hostile, to be honest.

But, since you replied, I wanted to tell you that your Reddit link actually had the solution. And for other users, the solution in the Reddit thread was:

"you can fix it by opening about:config in Firefox and set network.dns.disableIPv6 to true"

This worked, and now all sites open with Firefox and PIA running. So thanks for the Reddit link, and have a better day.