I don't know if it's a known issue (I can't read all the threads and even in a threads, sometimes all the posts) but I wanted to set the font to kobo Nickel (with 3.2.0) and I had huge line spacing even if it was set to zero. With 3.3.0, it seems to be fixed

but I became used to Malabar and now that it "works", I don't want it anymore