Firefox 68 has implemented the latest CSS Scroll Snap spec that has been revised significantly since the initial implementation was shipped with Firefox 39. While Chrome and Safari have already added the support for the new syntax, the changes in Firefox are not backward-compatible:
scroll-snap-type-yproperties have been dropped
scroll-snap-typeproperty has become a longhand, so the old shorthand syntax like
scroll-snap-type:mandatorywill stop working
Be sure to update your stylesheets accordingly for the new syntax if you have already utilized Scroll Snap.