One possibility (if it is not truly, all orders move into Q3) ...
In the manufacturing / supply chain world, there is the process of an ERP/MRP Regeneration. Regardless of the system (SAP, WarpDrive, Oracle MFG, whatever) under the hood will be a style of Manufacturing Resource Planning.
Basically the goal of these systems / logic is to align the supply of materials / parts / sub systems etc with output demand and scheduling of production. The goal is to maximize efficiency, maximize utilization and realization of labour / machining / production resources and well ... profits and delivery times.
Normally these plans are run at some repeating period (real time, nightly, weekly, monthly) in what's called a net change mode. Net change basically keeps revising the plan using previous inputs and any changes. This usually preserves a history of the plan.
Regen mode wipes the slate clean. Typical scenarios for a Regen are when errors in the data are piling up and affecting the production schedules, disruption of major critical supply chain(s) and major disruption to production capacities (say a critical process is down, such as a vital machine) or you run a style of production that is very one off (such as building very complex things) or very long lead time. Think airplanes, submarines, ships or nuclear plants etc
In a normal company, this mass move of dates for everyone would be a signal that a regen was done. But this is Tesla, so maybe someone spilled coffee in the data center or they are tacitly acknowledging everyone gets deliveries in Q3.