If you filled out the Canada Worker's Benefit (CWB) prior to entering the T2202, then the T2202 would reduce his refund. This is because if he attended school full-time for 3 or more months (13+ weeks) during the year, then he would not be eligible to claim the CWB and it would be removed from his refund. Since he was a full-time student for 4 months, he is not eligible to claim the CWB.
For more information, please see our TurboTax article.
Applying for the Canada Workers Benefit | 2022 TurboTax® Canada Tips (intuit.ca)
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