Wait Staff Required To Pay Minimum Tip To Back Of House (11%)

I recently learned of an Oregon restaurant that requires its wait staff to pay a minimum 11% tip on all bills to the back of house staff, regardless of the tipped amount. This means that if someone tips less than 11%, the wait staff owes money out of their pocket to make up the difference. This is causing serious issues at the moment because large construction crews are working on the property, having large meals, and leaving small tips. Servers are typically owing $10-$20 out of pocket on each of these bills. This all sounds highly suspect.

Edit: I should also clarify that the tip pooling is only for the back of house. Each server only receives the tips on their own tables. Each server is solely responsible for making up the gap to 11% of the bill total if tips do not exceed 11%.