I noticed something weird earlier. I'd taken to doomscrolling r/all and just resigning myself to removing the maximum 100 subreddits roughly in order of annoyance. I had 99 blocked subs before the blackout, and now there are only 69. I don't think private subs would disappear from there, so... maybe those 30 subs just got axed in their entirety.
Either way... nice.