You guessed it, it's another Rules update. Check here for more info

Tag changes for image #19506

Image		Tag	Action	Timestamp	User	Retained?
19506		+-SH solo female Unwatch Watch Unspoiler Spoiler Unhide Hide Sign in to Watch Filter 14451	Added	25 days ago	LightningBolt Stop! This user is a staff member. Ask them before reverting their changes.	Yes