Braking doesn't increase range. Rather the natural foot off pedal regen braking increases range. If you physically slam on brakes, I'm sure that doesn't help range.
The meter is presenting you the regeneration “rate” but what you’re thinking of is the regen rate integrated over time, I.e the amount of charge recovered during the process of stopping, which the meter is not showing you.
(Also, Tesla cars do have blended braking between region & friction...)