Tip Deductions

My grandson works as a tax preparer in a Deli/restaurant and gets paid a hourly wage plus a "promised tip" fixed amount per hour worked. All tips both cash and credit card from customers are collected by the owner.

His hourly wage and promised tip amounts are shown separately on his paystub and both are included in his W-2 as earnings which is taxed for both FICA and Medicare purposes. Does this tip earnings qualify as a reduction to earnings on his tax return per the OBBB? Thanks.