ceiling water stain cause 4

https://myroofleakvscondensationdeck.clearminster.com/posts/roof-leak-vs-condensation-how-to-tell-the-difference-and-what-to-do

A ceiling water stain is usually caused by a leak from above, like a burst pipe in the attic or a failing roof flashing during heavy rain. Sometimes it's a slow drip from a faulty HVAC unit or a bathtub overflow that seeps through the floor. The water travels along joists or drywall until it finds a low spot, then leaves a yellowish-brown mark as minerals and dust settle. If you spot one, act quickly because it can lead to mold or a collapse.