well the player might have been getting away with it for a long time
In my view it depends on whether or not the software provider knows about the existence of the bug
if you report the bug and a week goes by without any fix at all..........then unfortunately the software is merely 'so so' , so report it , see if they issue a fix......and if they dont send them an invoice for the amount you have lost with all players exploting this 'feature'
with the internet these sort of things must be fixed ASAP as people that is 'on the loop' find out immediately and honestly I would not feel a lot of sympathy for a sportsbook that is being ripped off due to a known issue that it has not been fixed for whatever reason