What is the ruling on zakat for a sum of $5000 that was paid to an investment company for a vehicle that has not yet been received, knowing that withdrawing the amount was not possible until the company's recent announcement?

If the purchase transaction was conducted through the salam method, then the amount paid is considered the property of the company, and the company must pay zakat (definition) on it for the period the amount was in its possession. As for the company's announcement allowing buyers to reclaim their money, this is a permission for annulment (iqalah). If the price is returned to the buyer through annulment, then there is no zakat due from him for the previous period because it was not in his possession.