Does your 2020 tax return include Form 8606? If not and you made nondeductible traditional IRA contributions for 2020, yes you'll need to amend 202 to report the nondeductible contribution(s). If your 2020 tax return includes the Form(s) 8606, there is no need to amend and you can just enter the amount(s) from line 14 of the 2020 form(s) when TurboTax asks for your basis after you indicate that you made and tracked nondeductible traditional IRA contributions in prior years.
Note that in TurboTax is is all to easy to cause TurboTax to silently delete you basis by mistakenly answering No when TurboTax asks if you made nondeductible contributions for year's prior to the current tax year. If you've been using TurboTax throughout and transferring in the previous year's tax return each year, this is how your basis got lost.
There is "our" IRA. IRAs are owned by individuals, so each individual will have their own series of Forms 8606.
