If I was overpaid in unemployment benefits but repaid them, do I report the full amount of unemployment compensation that is on my 1099-g, or do I put the difference?

You have to enter the full box 1 amount as it appears on your 1099-G.

Did repay it in 2020 or in 2021? If you repaid it in 2020, select Yes when TurboTax asks if you paid back any unemployment benefits, and enter the amount that you repaid. TurboTax will subtract the repaid amount from the total on your tax return.

If you repaid it in 2021, you will deal with the repayment on your 2021 tax return.

Keep in mind that for 2020 the first $10,200 of your unemployment benefits are not taxable. If the total benefits that you received, before the repayment, were $10,200 or less, the repayment will not make any difference in your tax because you are not paying tax on any of the unemployment benefits.