I call it a "bleach spot", it's a spot that has been bleached by bleach.

You wouldn't call it a bleach stain when a girl bleacher her b-hole, so I am solidly in the camp that a "bleach stain" is an oxymoron.

Bleach bleaches. If a bleach mark is a stain, then it added a stain.

No, you just need to stop churning for a while.