That is not a plane if you look close. That is thieving. The board layout had no copper there, but this can make the plating process more difficult to get consistent across the board. Usually this is added by the fab house to help them manufacture the board.
I watched the some of the analysis and Max completely dropped the brake. I think McLaren is correct in arguing Max intentionally carried too much speed so he could get the apex first, but did not have a chance to make the corner. So in my opinion Lando should not have picked up a penalty for that.
However, he should have picked up a penalty for his turn 1 move…