No, they’re not. No software company has ever needed legal cover for that and nothing changed in the legal landscape to create that need now. To pretend that there is such a need is to deliberately misrepresent the fundamental nature of what a product, such as software running locally on the user’s machine, actually is.

The only justification for having ToS is if Mozilla is transforming Firefox into a service that depends on communication with Mozilla’s servers themselves, which is absolutely not just “typing a URL into the URL bar!”