[franklekens]

I bought a few books that I then sideloaded onto my Kobo ereader.

Something has gone wrong with some of these, and it seems to have something to do with code tables.
E.g. there are random  signs popping up where there should just be a blank line.
Also, apostrophes are rendered as â. Very annoying.

Also, these  signs show up (for blank lines) in what looks like the improvised cover picture.
This cover picture shows up like this, with the  symbols, on the Kobo device *and* on the preview in the Calibre main window. But it does *not* show up like this when I open the file in Calibre. There, the cover looks normal, and apostrophes are also rendered correctly.

At first I thought this had something to do with the recent Calibre update with "improved" Kobo support. But one of the books I bought & sideloaded in the same batch does not display this problem, whereas the other three do. So I'm beginning to doubt that is the problem.

But what is, then?
I haven't changed anything in my configuration of Calibre (other than updating to 8.0.1) and/or the Kobo Utilities plugin.