What is paranoia about it?
They are using a browser fork that isn’t being maintained, so any current vulnerabilities it has will likely not be solved, including the one i know of that is currently being exploited and was fixed in firefox over a year ago.
I’m not saying that Firefox and other forks of it won’t get vulnerabilities, but as they are maintained, and this goes especially for Firefox which they are forks of, the vulnerabilities will likely be fixed in a timely manner.














That doesn’t mean that your carrier isn’t the problem.
Just like the person you replied to, I to can just log in to my carriers app on a new phone and get eSIM fixed there if my old phone is in an unusable state.