Billy Horschel wants to understand why some members of the LIV Golf Invitational Series are playing this week's BMW PGA Championship, a flagship event on the DP World Tour.
The DP World Tour, previously known as the European Tour, has not outright banned LIV players from competing in its events like the PGA Tour has done.
Horschel, an outspoken critic of the Saudi-backed LIV circuit, was peeved that some LIV players who had never previously played in Europe were on hand at Wentworth Club outside London.