I thought that one of the rule changes was a penalty if the third man into the tackle impacts below the knee. A move designed to protect the players knees from impact injuries. Seen quite a few knee or below last man tackles but don’t think I ve seen any penalties for it.

Or did I imagine the rule change ?

I thought so too, until I looked this up. Seems like not been adopted by SL yet.

Three more NRL rule changes introduced earlier in 2020 are being considered for the resumption of the northern hemisphere season:

When a team kicks out on the full, play will be restarted by a play-the-ball rather than a scrum;

The restart following a mutual infringement (such as the ball hitting the referee or a trainer) will be a play-the-ball rather than a scrum;

Restrictions on the legal point of contact for a third defender in an upright tackle, which must now be above the knee.

The RFL and other members of the Laws Committee will continue to monitor the effectiveness of these rule changes in the NRL over the coming weeks, allowing for flexibility before the recommendations are presented to the RFL Board.