Reddit's overlords decided that a whole bunch of 3rd-party stuff that made the site more accessible or just better to otherwise use needed to start paying for that functionality. Which, in itself, wouldn't have been a problem per se. Except that that they decided on an absolutely excessive price that was clearly meant to either drive those third parties out of action entirely or give Reddit a level of income all out of proportion with what they were providing on their end.

A number of Reddit's (unpaid) mods decided that this was not acceptable and blacked out their subs for a couple of days in protest. And a few subs have decided to remain dark even after the initial 48-hour protest period. Of course, since not many of the biggest subs joined the protest, the actual effectiveness was debatable.

However, one definite consequence was that Reddit's overlords had their noses suddenly and unpleasant rubbed in a great big, stinky pile of fact that their useful idiots (mods and user alike in that category) could potentially enact a level of site disruption that threatens their ability to sell advertising or monetize content.

So they have decreed a new policy that the moderation team of any sub that remains dark (or, in the future, otherwise proves intractable) can be removed and replaced with more "acceptable" moderation teams. Now this isn't much of a policy on the face of it, since Reddit always had the power to shitcan mods at will. The wrinkle here is that this policy puts more of that shitcan power in the hands of a sub's users. I don't know the exact details of how this is supposed to work--or even if those details have yet been released in general--but I can all too easily see this being abused by the members of subs known for brigading behavior.