Magnus vs Nodirkbek | question on a move

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phvniv2k

can someone please explain  how this move is valid  in the game ( Move # 77) ? 

https://www.chessgames.com/perl/chessgame?gid=2179948

Black to move. Last: 77.Ka6

Moving  White King to cross to a black  pawn should be check.  How that is allowed?  Please suggest some material  to understand this. 

Onlysane1

The game is shown from white's perspective. The black pawn is traveling downwards, threatening the two diagonals below it. The diagonals above it are not threatened by the pawn.