Unless you had two or more employers in 2021 and the total of all SS taxes withheld was $8,854 or more then none of your SS taxes are entered on a tax return so there is no reason to amend a 2021 return.
Look carefully at the W-2c. Even though the additional Social Security tax came out of your pay in 2021, the W-2c should be for 2020, not 2021. Your employer is just a little late sending it out. The Social Security tax deferral under the CARES Act was in 2020.
You are not doing anything wrong. The amount of Social Security tax does not affect your federal income tax (refund or amount owed) unless you had more than one employer in 2020 and you had excess Social Security tax withheld. If you had only one employer, and the only change on the W-2c is the Social Security tax in box 4, it does not affect your tax return and you should not file an amended return. If you had more than one employer, and the total amount of Social Security tax withheld by all employers was $8,537.40 or less (for 2020), do not file an amended return. You would only file an amended return if you had more than one employer and the total Social Security tax withheld, using the corrected amount on the W-2c, was more than $8,537.40.
If you filed as married filing jointly for 2020, add up only the Social Security tax that you paid yourself. Do not include your spouse's Social Security tax.