Firefox isn’t as secure as Chromium browsers due to its internal sandboxing and site isolation being substantially weaker (especially on Linux). If you are on a Linux machine, I recommend you use Brave with no ad blocking extensions because first, it comes with an ad blocker by default. Also, the more extensions you have, your attack surface increases.

If you are on Windows, you should be using Microsoft Edge paired with UBO Lite as it offers the highest security and UBO Lite doesn’t have access to the site data. If you are concerned about the telemetry of using Edge, you can turn it off and if you’re still paranoid, you will have to switch to Linux at this point.