I've read anecdotes that China is making new containers instead of accepting old containers. This could be because buffers aren't getting them back in time or because China needed a new market for steel
Containers have a lifespan, so China has always been making containers. When containers don't come back you can buy a new one. Shipping them back empty is a lot cheaper than buying a new one, but only if you can get them shipped back. The price to ship a container back empty is low enough that some ships decide it isn't worth it.
