The typical word for the general phenomenon of employees leaving an organizing is attrition.

This word in reality can have a more significant meaning in the sense of loss of intellectual assets, causing a reduction in the company's overall capabilities.

So, I think you can use attrition in its primary sense or its metaphor here.

The typical word for the general phenomenon of employees leaving an organization is attrition.

This word in reality can have a more significant meaning in the sense of loss of intellectual assets, thus causing a reduction in the company's overall capabilities.

So, I think you can use attrition in its primary sense or its metaphor here.