"the taxpayer has 2 jobs and had the maximum taken from Job #1"

$23,000 and it was taxed? In 2024, the 401(k) contribution limit is $23,000 for employee deferrals and $69,000 for combined employee and employer contributions. For those age 50 and older, an additional $7,500 catch-up contribution is allowed, bringing the employee deferral limit to $30,500.

"and $5806 more taken from Job #2"

It's a limit per tax payer. Not per employer.

"So, it was not taxed"

This new employee amount at the new job wasn't taxed?

"and shows up in software demands that it be entered in excess deferrals."

What is your taxpayer's age?

In 2024, the mega backdoor Roth limit is $69,000 or $76,500 (includes $7,500 in catch-up contributions if you're 50 or older), compared to $23,000 or $30,500 if you're 50 or older in pre-tax contributions.

The mega backdoor Roth strategy allows you to contribute after-tax dollars to a 401(k) up to the combined limit, which can then be converted to a Roth 401(k) or Roth IRA.

First, take the allowable limit of $69,000; subtract your salary deferral of $23,000, and then deduct from that any employer match. The difference gives you the amount you can add after tax.

"However, it was moved to a Roth just a day ago."

That's got no bearing on if they were overcontributed in the first place.