I disagree that it’s a euphemism. It’s a term with a specific meaning
Ethnic cleansing has been described as part of a continuum of violence whose most extreme form is genocide. Ethnic cleansing is similar to forced deportation or population transfer. While ethnic cleansing and genocide may share the same goal and methods (e.g., forced displacement), ethnic cleansing is intended to displace a persecuted population from a given territory, while genocide is intended to destroy a group.