Sorry but that isn't a violation. Especially if you the user checked the box. Once you do that you assume all responsibility for doing so. By Default that box isn't checked. Also by installing you agree to their TOS remember that as well.

Hi chrisw63, do you mean web form history, where Firefox shows a drop-down list below the field of previously saved entries for that field? The default setting in Firefox is to have the Form History feature enabled. If you previously disabled it, it should have stayed disabled, unless your Firefox was reset during the update (but then you probably would have noticed many more settings changes).