What does the OIC acceptance letter say?

The last one I saw said "Under the conditions of the offer, we will keep any refunds or
credits you may be entitled to for 202X or for earlier tax years,
including refunds you may be entitled to receive in 202Y for any
overpayments you made toward tax year 202X or earlier tax years . We
will apply any refunds or credits to your liability, not to your
accepted offer ."

X is the year the offer was accepted. Y = X+1.

So probably no refunds will be received by client.