"1. IRA contribution (other than amounts in boxes 2-4,8-10,13a and 14a) ----$4,000"

What matters is Box 1 for the tax year you are asking about for making contribution. Your client's previous plan manager either reported the rollover incorrectly, or your client already made $4,000 in 2022 contributions.

Look at Box 7.

Perhaps this person has another 5498 that reflects the rollover? Because the one you described is reflecting new contributions already made for the year; not rollovers.

That doesn't mean they can't contribute more. You have to reduce their total eligibility by the $4,000 already made. Or, they need a corrected form that properly reflects the 401(k) $4,000 was Rollover Box 2.

Something here is not what you described. The taxpayer might need to get more info.