If you are single, you would be entitled to a stimulus payment of $600 (round 1, paid from April-July 2020) and $600 from round 2 (paid from December 2020-February 2021--the round 2 payment is considered for 2020 even though most people weren't actually paid until 2021.). The IRS would also mail you a letter 1444 and 1444-B to state the amounts of the payments.
Turbotax asks if you received these payments, if you say no, Turbotax will claim a rebate for you.
If Turbotax claimed $600 and the IRS removed it, that indicates that you told Turbotax that you only received $600, but the IRS thinks they sent you $1200.
If you received $1200 in stimulus payments, then you made a mistake on your tax return and are not entitled to additional funds. If you only received $600 but the IRS thinks they sent $1200, then you have to trace the missing payment, you can't get it on your tax return. See question F3 here,
https://www.irs.gov/newsroom/2020-recovery-rebate-credit-topic-f-finding-the-first-and-second-econom...
