Also applies to any xAB or “normal” apps which people are preparing presently.
Google has changed the rules again. If you are preparing an app now, please allow yourself some time to read up and adapt your artwork:
The page is saying this:
Before June 17, 2019, developers must use the Play Console to apply the new specification to their icons.
but is also saying this for new artwork to be uploaded:
Uploading an icon per the original specification will not be allowed as of May 2019.
This gave me frustration a few days ago, when I was all ready to launch an app, and then got stuck and had to rework our icon from our logo.