What if i already file my taxes for 2020 and now I hear that my unemployment benefits that I received are no longer taxable income up to $10k, what do I do?

You will have to amend the tax return that was filed to get the unemployment compensation exclusion.  But not yet since the IRS has not provided guidance on the procedure.

See this TurboTax support FAQ for information on the American Rescue Plan - https://ttlc.intuit.com/community/tax-topics/help/how-will-the-stimulus-package-impact-

Great. thank for you for the information.