Neither of those things matter. If he is the owner (co-owner) then he is simply paying the expenses on his own property. (The payment may technically be alimony as well, but that has no tax implications if it is or isn’t because the divorce was finalized in 2019.)
The payment is not taxable income to you or deductible by him. But, he can take an itemized deduction for half the mortgage interest and property taxes, and you can deduct the other half.
