It is bad quality control as according to Apple's product images, by design, it should look like this:
View attachment 956761
So yes, the band should fill the gap perfectly by design. If it was a €15 knock off I could live with it, but the gaps on the sides are unacceptable at €100. Bad quality. It's best to wait a little till these bands are how they are supposed to be, especially as you mentioned all of them are this way. While every other band in the past always filled the hole perfectly in line with the case (even cheap knock offs).