However, if someone is going to stop using Firefox because of these new terms, I would assume that person is already not using any products or services from Apple, Microsoft, Google, Meta, etc. Seems pretty hypocritical otherwise.
Those companies are known to be privacy hostile companies. Mozilla/Firefox, not. In fact, Mozilla claims the reverse!
For them to abandon privacy, is a betrayal, it's backstabbing behaviour. Feeling betrayed and wanting nothing to do with said software, as a result, seems normal to me.
Or in slightly different terms: If I wasn't using Chrome because of privacy issues, then Firefox losing the privacy advantage means they just ditched the only reason I was still using their product.
If Mozilla is abandoning their pro-privacy stance, they still have at least one thing (in my opinion) going for them over Chrome: Manifest V2 extensions. For now, at least.
The type of product/service matters here. We're talking about a browser here, with the name "User Agent" being popularized by Mozilla,for fuck's sake.
I don't use Google or meta services. I do use apple's and Microsoft's OS, but last time I checked, neither of those required me to give a nonexclusive, royalty-free, worldwide license to Microsoft or Apple for all the data that I input into their OS - even when it goes through the TCP stack. Yet this is what Mozilla has in their own license. (and yes, before you ask, I did review the macOS TOS. You can find them here if you're interested: https://www.apple.com/legal/sla/docs/macOSSequoia.pdf)
For all their problems, MS/Apple TOS are usually for things that interact with their services. Here, firefox's new TOS is ridiculously wide and touches things that do not interact with Mozilla's services, for no reason.
There's also a matter of trust; Google, Apple, Microsoft and Meta are trustworthy in the sense that I have an expectation of them that's already fairly negative insofar as user privacy is concerned. The correct response to "Google tracks you" isn't one of shock, it's one of acknowledgement because it's to be expected at this point. Google hasn't ever pretended that they aren't selling your profile to the highest bidder, so while I have issues with that, they're more in the sense of "it should be illegal to do this in general" rather than "I could never have foreseen this outcome". Same with Microsoft, Meta and especially Apple.
Mozilla was operating under a different set of expectations up to this point - they always made a big deal of protecting the user from bad actors, put privacy pretty front and center (in the sense of not selling your shit to data brokers/using it for advertising) and in general were fairly reliable on that. This dynamic seems to be shifting in a new direction that's closer to the other four mentioned companies and that's violating the trust they've build up over the years. It makes you wonder what Mozillas word is now worth and what it'll be worth in the future.
Hence why people are considering leaving; trust is a pretty major factor in that sort of decision. It arrives by foot (is hard to gain) but leaves by horse (is easy to lose).
However, if someone is going to stop using Firefox because of these new terms, I would assume that person is already not using any products or services from Apple, Microsoft, Google, Meta, etc. Seems pretty hypocritical otherwise.