During execution the team’s velocity has decreased and many items are waiting in the testing queue. The project uses a hybrid approach and only a few sprints remain. What should the project manager do?

The best approach is to work collaboratively with the team to identify the root causes of the decreased velocity and the testing bottleneck. This aligns with agile principles of self-organizing teams and continuous improvement. The team members are closest to the work and best equipped to diagnose the issues and propose effective solutions, which could include process adjustments, skill-sharing, or re-prioritization. Providing testing training to all team members might be a long-term solution but won't address the immediate bottleneck in the few remaining sprints. Adding a new team member with testing skills could help, but it introduces onboarding overhead and might not be feasible or efficient for a short remaining duration. Extending the sprint duration would mask the underlying problem rather than solving it and could negatively impact the project schedule.