After-tax money contributed to the 401(k) would only be entered in the section for determining any Retirement Savings Contributions Credit, but someone making after-tax contributions to a 401(k) probably doesn't qualify for that credit.
Although after-tax contributions to the traditional 401(k) account are different from elective deferrals, it's unlikely that your employer would accept an after-tax contribution made in 2023 as a contribution for 2022. Allowing that would make a mess of anti-discrimination testing.
To be clear, you do not get a deduction for after-tax contributions made to a 401(k).
