I feel for Ashley here. She likely had no say in the matter and is being tasked to defend this change.
There is only one way to fix this short term which is to roll back the TOS.
Long term would be to guarantee to keep the MPL as the governing license for both the source code and executable.
Acceptable solution would be severely limit the license users would have to give to Mozilla, both time bound and use bound.
you hereby grant us a ~~nonexclusive, royalty-free, worldwide~~ limited, royalty-free license, used for the duration explicitly necessary to allow Firefox ~~to use that information to help you~~ navigate, experience, and interact with online content as you indicate ~~with your use of Firefox~~, not to exceed execution duration of the browser, or one day, whichever is shorter.
But again, absolutely no license should be necessary. The browser is not a legal entity and I should not need to give Mozilla a license for my data.