@Ginius
The file is still not available, on the part of joomshaper nothing has been done yet.
The problem was first reported 8 months ago and since then nothing has happened.
Presumably an XML will become available in 4 months with the first update. Until then, the only thing to do is to ignore the message, otherwise you will not see when an update for the template becomes available. :(
With the assumption that you have not subscribed to the newsletter of Joomshaper or there should be no newsletter/blog to it.
Nevertheless, I wish you a happy and successful new year.