Just to point out, that "the whole point of Firefox" is to make the network requests I want.

eg from my perspective it's a tool like (say) cURL that has a specific purpose.

It's a subtle difference, but an important one. :)

I'm mainly just replying to the poster that attempted to say that since Firefox already makes network requests, ~anything should be ok.

My guess is that Firefox will not try to check for updates or other things if it notices that the detectportal-request was not successful (i.e. the user is not logged into the hotel-wifi or something like this yet).

So... guessing here, that particular request would be checking if the domain for the Firefox update check itself has a valid cert.

If that's not what it's checking, hmmm...

And you can prove this how?

All I'm saying is think twice before blindly trusting a tech company, because Mozilla is no longer the fun and friendly company we once knew. They are very much a rank and file data mining company now, generating tons of cash, and being infiltrated by CEO and marketing types.