"Huge" may be an overstatement. They laid off 6,000 people which is obviously a lot of individuals losing their jobs but only represents 3% of the company. In today's market a 3% layoff is comparatively small.

I've never heard of a company doing a layoff in the way you describe, eliminating thousands of roles and immediately moving those people into open roles throughout the company. It assumes the employees are fungible and will be a good fit for any open position and would lead to everyone knowing the layoff is coming well before its announced.