The assumption in the WPA rules is that there will be a referee at the table and the referee will make the determination of what happened. In case there is no referee, the following part of the regulations (separate from the rules) is applicable:
If a dispute arises between two players in an unrefereed match, and the area referee is asked to make a decision without having seen the cause of the dispute, he should be careful to understand the situation as completely as possible. This might include asking trusted witnesses, reviewing video tapes, or reenacting the shot. If the area referee is asked to determine whether a foul occurred and there is no evidence of the foul except the claim of one player while the other player claims that there was no foul, then it is assumed that no foul occurred.
I think that if they were able to review the video -- which is often not easy during a televised/streamed match -- a foul would have been called. It appears to me that the cue ball did not return to the side cushion after hitting the one ball.
The rules and regulations can be found here:
https://wpapool.com/
https://wpapool.com/rules-of-play/
https://wpapool.com/rule-regulations/
It is surprising to me how many players have never read through any set of rules.