ARPA kinda sorta anticipates that there will be situations like this and tells IRS (Treasury) to try to do something about it with Regulations. However, it also says that once an advance payment is made, it can't reduce the allowed credit below zero.
“(h) Regulations.—The Secretary shall prescribe such regulations or other guidance as may be necessary or appropriate to carry out the purposes of this section, including—
“(1) regulations or other guidance providing taxpayers the opportunity to provide the Secretary information sufficient to allow the Secretary to make payments to such taxpayers under subsection (g) (including the determination of the amount of such payment) if such information is not otherwise available to the Secretary, and
“(2) regulations or other guidance to ensure to the maximum extent administratively practicable that, in determining the amount of any credit under subsection (a) and any credit or refund under subsection (g), an individual is not taken into account more than once, including by different taxpayers and including by reason of a change in joint return status or dependent status between the taxable year for which an advance refund amount is determined and the taxable year for which a credit under subsection (a) is determined.
