It’s difficult to see your max v mechanics because of the angle, but it looks like you aren’t following the step over, drive down. It looks like you are skating your feet a little which is braking your momentum if correct. Certainly for a Rugby player your acceleration mechanics are wrong as you need to get up to max speed quicker than a sprinter would. I would work on max speed mechanics drills. The dorsiflexion issue should be resolved by that as well if you do them correctly. It takes time to embed the mechanics though. There are no quick fixes.