Face-on putting (also known as side-saddle putting or straight-forward putting) is 100% legal by United States Golf Association’s official rules and can be used in any tournament around the world so long as the player does not anchor the club or intentionally hold a forearm against the body to create an anchor point.
This is not to be confused with croquet-style putting, which was banned by the USGA back in 1968 by amending Rule 35-1 after aging golf legend Sam Snead adopted it in an attempt to overcome the yips.
However, the USGA Rules Department changed positions on its croquet-style putting ban with Rule 16-1e, which is limited to the putting green. Since there is no similar prohibition for a stroke of this kind made from off the putting green, a golf player can use a croquet-style putting stance from off the putting green.