I also just got the update, although not "officially" from reMarkable ... somebody out there remembered that I was looking for the update image's actual filename and sent it to me, so both of my tablets are now running 3.8.2.1965. (Somebody should send the filename to the developer of codexctl as well.)
I had been using 3.8.0.1944 on my "experimenting" tablet for the past few weeks. With RCU d2023.001(j) I clicked the "use it anyway" button (I forget the exact wording) and it seemed to work just fine. Of course now with the updated "compatibility table" I'm not seeing that warning anymore.