I was attempting to use the ProtonVPN Firefox Browser Extension and DNSLeakTest would still show my current ISP DNS every other extended test when I was connected. Attempting to use the about:config → network.trr.mode = 3 setting would work for about 10 minutes before the entire internet service stopped working.
I’ve now started using the split tunneling feature via the windows app to only run Firefox through a VPN tunnel and this seems to be accomplishing everything I wanted from the browser extension. So what’s the caveat of using the Windows App this way? I understand this method won’t let you split tunnel via tabs directly like Firefox VPN does, though the ProtonVPN Browser Extension doesn’t let you do this yet either.