A quality manager needs to be able to make quick decisions and act on them.  In such cases where that the defect rate is suddenly surging or showing such trends, one should analyze the type of defects/bugs being raised, consider the logs and review recent changes, triage the defects with the development team/leads, isolate the most recent updates to the application/code with the help of developers, perform and document the root cause analysis (RCA) along with actions taken to ensure planning such outcomes in future as well