I’ve just had a reply to my case :
We understand that you would want to know how to calculate the Estimated delivery date as you see the delivery date of the ASIN : 0853290822 as Arrives between May 13-16 on the product detail page.
Due to COVID-19’s impact on carrier delivery times, we may temporarily increase the standard transit time and thereby extend the delivery promise to our customers. This will affect only the delivery promises that customers see on the Amazon website and not the handling time in your Seller Central account. As long as you ship the items by the promised shipped date, your performance metrics will not be impacted.
We have posted answers to your frequently asked questions about Amazon’s policies in response to COVID-19.
I’ve asked for a link to the relevant section