How can my refund be a lot more than what was withheld during 2021?

There may be various credits you are eligible to receive, such as the Earned Income Tax Credit, the Retirement Saver's Credit, the Child Tax Credit, the Other Dependent Credit, the Child and Dependent Care Credit, etc.

Look at your tax return for how your refund was calculated.  Also, check that the amount of taxes withheld reported on your W-2 is correct in TurboTax.

You can view your Form 1040 at any time using the online editions. Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

But also check for any data entry errors, especially commas and decimal points.