You can only use 2019 if 2019 is higher than 2021 earned income.

Election to use prior-year earned income
You can elect to use your 2019 earned income to figure your 2021 earned income credit (EIC) if your 2019 earned income is more than your 2021 earned income.

https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/earned-income-and-earned...