he 2019 form is "NOT" entered anywhere on your 2020 tax return. If you did not claim it on your 2019 return and you want to, then you'll have to amend your 2019 tax return to add it.
If that 2019 form 1098 is for what used to be your primary residence, then you may want to ensure you're not wasting your time with amending. If adding that 1098 amount to your SCH A itemized deductions on the 2019 return does not make your total itemized deductions greater than your standard deduction, then it will make absolutely no difference to your 2019 tax liability what-so-ever.
