The leak-to-mold connection
Yes. Water leaks are one of the most common causes of mold, and when a landlord's unrepaired leak leads to mold, the landlord is generally responsible for both the leak and the mold that follows.
Mold can start growing within a day or two of water getting in, feeding on damp drywall, wood, and carpet. Because the leak behind it is usually the landlord's to fix, the resulting mold is typically their responsibility too. Fixing only the visible mold without stopping the water just lets it come back, so a real repair addresses the leak first.
If a leak in your home has led to mold, document both the water source and the mold with dated photos, and report them together in writing. That shows the connection between the landlord's unrepaired leak and the mold. If a leak has caused mold and your landlord will not fully address it, a free review can explain your options.
This is general information about California tenant rights, not legal advice. Every situation is different.