Sync availability first
A feed advertising something nobody can buy is wasted spend and a misrepresentation risk. Check how fast your feed app updates — daily is often not fast enough during a sell-out.
Exclude the product, keep the campaign
Pausing entire campaigns throws away conversion history you will want back. Exclude the item, move its budget, keep the structure intact.
If it is your main seller
Expect the account to drop and do not read it as a performance collapse. Note it, so next month’s comparison makes sense.