The loan from 2020 was not forgiven evidently, but it is not taxable income since it is just a loan. Consequently, you don't necessarily need to amend your return for 2020 since your taxable income did not change. You can amend it if you want to change the amount of the tax-exempt income reported on line 16(b). You don't need to report it in 2021, since it won't affect this year.
For the PPP grant in 2021, you enter it the same way you did in 2020, on line 16(b) on your form 1120-S, schedule K.
The loan payments are not entered on your income tax return, since they aren't deductible, but you can enter the interest expense associated with them on line 13 of the first page of form 1120-S.
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