There’s a lot of different ball markings these days. It’s almost an artform in itself. Most are to identify your ball in case you find yourself next to another ball of the same brand but some are to help line up putts. All perfectly legal of course. There are specfic golf ball pens and little devices that help you enscribe them onto the ball easier. Some golfers put their initials on the ball while others prefer little dots.
A golfer in my group last week had “Go Home” written across his ball.