Each tax year is separate. The fact that you became a W-2 employee for tax year 2022 has no bearing on tax year 2021. What you say is that for 2021 you were paid as an independent contractor and received a 1099NEC. If you received even $400 of income as an independent contractor for 2021, you have to enter that on a 2021 tax return and pay self-employment tax for Social Security and Medicare, and perhaps pay ordinary income tax, depending on how much you earned.
If you did not file a 2021 return, or prepared 2021 incorrectly then you either need to prepare a return for 2021 or amend the return you filed.
https://ttlc.intuit.com/community/self-employed/help/how-do-i-report-income-from-self-employment/00/...
https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922
https://ttlc.intuit.com/questions/2902389-why-am-i-paying-self-employment-tax
https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c
https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct
https://ttlc.intuit.com/questions/1901110-do-i-need-to-make-estimated-tax-payments-to-the-irs
See this TurboTax support FAQ for amending a tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
