Carbon Tax Refund Says Uncle Owes $$

Cross posted

So my family member is a plumber in alberta and they recieved this notice for a rebate that says they owe money. I didn't think small businesses were charged like this? Is this a tax thing?

Amount owing is $4500 and his picture says it is owed by Dec. 14, 2024 without penalty.

Does this make any sense? Or is this an accident.