From Canon Japan (translated):
Apology and information regarding product supply status
Updated: May 18, 2023
Thank you for your continued patronage of Canon products.
Currently, we have received more orders than expected for each of the following products, and due to the impact of global supply of parts, delivery delays are occurring. Expected that the new product RF100-300mm F2.8 L IS USM will take a lot of time. We apologize again for making our customers wait so long. We will continue to take measures for stable product supply so that we can deliver products as soon as possible. Thank you kindly look forward for your understanding.
Product Name – About Supply
We are planning to ship sequentially, but it is expected that it will take a considerable amount of time to deliver. Even if you have already placed an order, it may be difficult to deliver it within 2023.
RF400mm F2.8L IS USM
RF800mm F5.6L IS USM
We are planning to ship in order, but it may take longer than usual to deliver.