> I've noticed quality issues in your code recently...

Why is it always the report who is the source of the problem and not the manager?

How about "I've created a toxic work environment and put my reports under a lot of stress. And I have not given them any opportunities to grow and learn new skills. I am planning to do better..." Words that will never come from the mouth of a manager.

Have a hard conversation with yourself first before blaming the reports.