I noticed that my 2020 federal refund is higher than what Turbo Tax said it would be. Any idea why?

[Mike9241]

possibilities are almost endless.   a small additional refund would likely be because the IRS was tardy in making your refund and paid you interest (taxable when filing your 2021 return).  if rather large I would check your tax return transcript using the IRS website. it will show amounts you reported and amounts per the  IRS computers.https://www.irs.gov/individuals/get-transcript 

[rjs]

If the additional refund is something other than interest, the IRS will send you a letter explaining what they changed on your tax return. You should get the letter two or three weeks after you got the refund.