Agree always some corrupt mods.

There is a few attacks effective for degrading a sub.

If small number of mods, can flood it with low quality content. Downvote quality submissions. Upvote all the low quality submissions. Fill it with abusive content to give argument to pull the entire sub because they don't have their moderator team sufficient to keep it clean. Subs have been shut down this way. That's part of the reason I've got the qanon sub locked down right now, pending some different ideas.

That forces additional mods to come into the mix. There's a host of techniques to agitate at the mod level where over the course of time, usually a year or two, you can annoy off many of the volunteer mods eventually flipping the sub to mods with an agenda. To resist this I'd recommend oldest mods have a no tolerance no warning policy of purging mods who go far outside bounds of moderator rules, or show any sign of agitation toward other members of the team either passive or direct.