IronFox, the Android hardened Firefox say so and provide some sources.

https://ironfoxoss.org/docs/limitations/#security

(/j)

In all seriousness though, this sums it up quite well: It is a few years old, but most of the problems still apply https://madaidans-insecurities.github.io/firefox-chromium.html

I said measurably because I do remember seeing benchmarks somewhere about the browser security, but as of now I can't find them. That said, while Firefox is worse, from a security standpoint, than chrome, it's generally more private (letterboxing, resist fingerprinting, etc.) but for me, the security tradeoff isn't worth it.

I know a lot of people probably won't believe me when I say this, but I do like Firefox (a lot more than Chrome and its derivatives) but when you can't sandbox browsers without significantly weakening the browser's sandbox (a little unintuitive), I choose to put security and browser integrity above personal preference.

If you or anyone else wants to use firefox, it's not like you're instantly going to compromise your machine. Firefox just lacks a lot of the security that chrome has, and thus has a greater potential for exploitation.

I measured it with a ruler and it's about 3 inches less secure.

IronFox, the Android hardened Firefox say so and provide some sources.

https://ironfoxoss.org/docs/limitations/#security

His proof? a payslip from Alphabet.