in this case they've been citing manufacturing shortages..
They revoked that on tirzepatide.. then subsequently put the allowance back in place after the compounding pharmacies challenged the true availability.
But it's a matter of time where a more definitive solution will be needed (months?).
FDA is also throwing out concerns publicly about the safety of compounding pharmacies, which appears to be more of a PR ploy to be used to justify when they crack down on them.