Thanks. But the issue was that I was trying to update using the Software Manager and it showed no update to FF. Using the Synaptic Package manager, I was able to update to 136.x.
OK, good. If either of those repositories allowed it to be installed then it should be openly reviewed and audited for security already.
Something interesting I found out about Mint when I first got it was that the default install of FF it came boxed with was a “tuned” and more secure version of FF. It was unique to Mint. But as soon as you updated it from the Ubuntu repository to a newer version FF it was no longer a unique to Mint version. But I don’t know for how long they continued to do that as newer versions of Mint came out.
But for quite awhile it was uniquely described as “Mint’s version of FF” and was supposed to be more secure than the vendor version. Mint has been pretty good about detains like that. That is why they dropped support for SNAP. It was insecure and they didn’t want any part of that insecurity.
https://lwn.net/Articles/825005/