"All European market production is being consolidated to Japan, where the company is based"
Japan just signed a major trade deal with the EU which would abnegate them from the need to actually make any cars in Europe anymore, since they can be imported into Europe sans tariffs.
Ergo - this is a story about how an EU/Japan trade deal is causing the closure of plants across Europe.
Clearly Brexit might be part of the calculus but there's no evidence to suggest how they are related.
You've offered no evidence or logic, and neither has the article. I don't think there's any clear reasoning on how Brexit factors into this.