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

Tag changes for image #21378

Image		Tag	Action	Timestamp	User	Retained?
21378		+-SH female focus Unwatch Watch Unspoiler Spoiler Unhide Hide Sign in to Watch Filter 1898	Added	22 days ago	LightningBolt Stop! This user is a staff member. Ask them before reverting their changes.	Yes