Speak with the vendor and explain that constant updates are impacting the project and request an action plan to minimize the changes.

Schedule a spike meeting, conduct risk assessments, and incorporate them into the backlog to help with risk mitigation.

Explain to the project team that the vendor's updates are something unpredictable, and the team must continue working on the project.

Schedule a retrospective meeting and conduct a risk assessment with the team, implementing mitigation tasks before the next sprint.