PMP Practice: Monitor budget variations and work with governance process

Bayani Villanueva-Cruz is managing an agile project at Photon Drift Inc, a mobile app development company building a health tracking application. During the fourth sprint retrospective, the team reports they are consistently delivering only 60% of planned story points. After investigating, Bayani discovers the team is spending significant time refactoring poorly written code from earlier sprints to support new features. The product owner is pressuring the team to maintain velocity to stay within the fixed budget approved by executives. The team's burn rate shows they will exceed budget by 25% if current trends continue. The product owner has already been informed of the technical debt issue two sprints ago but prioritized new features instead. Which approach would be MOST effective for addressing the budget variance?