I read in another post a while ago that there was some issue with a Windows update that caused it not to register as Windows. It was then corrected in a subsequent update. So the Unknown bump is just Windows.
Edit for reference: https://gs.statcounter.com/os-market-share/desktop/worldwide/#monthly-202301-202307
I loved Textra. It’s not their fault, but I really love RCS support, and right now that’s basically Google Messages and a handful of preinstalled carrier messenger apps (if I’m not mistaken). I loved adding a 3 second delay on sending texts - I always seem to see typos as/after I hit send. 😂