Nine months ago Customer Deposits were $942 million. At 3/31/19, Customer Deposits were $768.3 million. That's over an 18% decline despite recently opening the reservation window for SR+s/SRs in early March, and for MYs in mid-March
"Customer deposits primarily consisted of cash payments from customers at the time they place an order or reservation for a vehicle or an energy product and any additional payments up to the point of delivery or the completion of installation, including the fair values of any customer trade-in vehicles that are applicable toward a new vehicle purchase."
In prior filings, Tesla has stated they will not ship cars to foreign jurisdictions until paid in full, including applicable duties, taxes and tariffs.
The decline in deposits may not have been necessarily caused by lower demand, but lower demand should not be ignored as one of several possible explanations.