I used ‘add products’ today for the first time in a while (I normally just use the ‘sell here’ button or relist from my inventory).

Amazon have made some less than useful changes to the ‘add a product’ page.
You can no longer enter the name or EAN/barcode of a product directly to see if it is already in the catalogue.
This was often the only way to find ‘currently unavailable’ products/titles. You have to go through the (often inadequate) categories.

There is also a weird square grey button that appears not to do anything apart from produce a thin red line if clicked…: