Been looking into FSE themes lately, and I have so say 9.6 is a bit of a mixed bag for me. It's great to see patterns now available in the site editor, but the way that separate block stylesheets are now loaded seems to be a step backwards IMHO. Previously a FSE theme had the "style.css" stylesheet containing styles/layouts for all the various blocks to do a lot of the heavy lifting, now in 9.6, FSE themes have only the "common.css" stylesheet instead. I understand it has been done like this to reduce wasted resources so that only the required styles are loaded if a post contains a particular block(s). The issue is that now a FSE theme needs to have it's own separate stylesheets for each and every block, resulting in FSE themes now appearing to be broken. The way a theme's library of styles are rendered is also weird, with all the stylesheets rendered inline in the header, and then additionally the required block specific styles right after the opening body tag.