Why a failing ceiling is an urgent hazard
Yes, and it is dangerous. A sagging, bulging, or collapsing ceiling is a structural safety hazard the landlord must address urgently, because a ceiling that gives way can cause serious injury.
Ceilings can fail from water damage above, structural problems, or age. Once a ceiling sags or bulges, it can collapse suddenly with little warning, bringing down heavy debris. Stay out from under a sagging ceiling, move people and belongings away, and report it to your landlord as an emergency.
Repairing the ceiling and the underlying cause — whether that is a leak, framing failure, or age — is the landlord's responsibility. If someone is hurt when a ceiling collapses, that can support a separate injury claim on top of the habitability issue. If your landlord will not act on a sagging or collapsing ceiling, a free review can help you understand your options.
This is general information about California tenant rights, not legal advice. Every situation is different.