How is it reasonable? Firefox is a MPL licensed software. Why would they suddenly need a ToS if it is just a software? The speculation is that they are going to expand their data collection for ads and covering their ass via this new ToS.
For example, the point about them getting "royalty-free, unrestricted access to your inputs" is almost certainly to protect against frivolous lawsuits along the lines of "I typed something in the Search Bar and Mozilla copied it and that violated my copyright and so I want $1 billion".
Again, you're free to make your own fork, in which case you're not bound by these terms.