Also make sure to qualify this with actual examples of underperformance:
“In March you gave a three-week estimate for roadmap item X, but it wasn’t completed until June. Amy from team Y reached out to me several times with questions about its status, so communication hasn’t been up to your usual standard.”
If the manager doesn’t give the report something concrete to reflect on, they will only create more vague angst and frustration that will accelerate that person’s exit plans.
Offer help: “What do you need to get unblocked?” “Let’s sit down together and see if we can figure this out.”
Hold them accountable: “I understand, but we need to be keeping our partners up to date.” “Can you give me a date for a date?”
Teach: “Here’s what I recommend…”
Etc. You as a manager should be actively helping your employee work through the issue - whether it’s external or internal (growth for them).