GA4 has separate user key event rate (users with a key event ÷ users) and session key event rate (sessions with a key event ÷ sessions). The denominators differ; state which one you report.
Key event rate
GA4 has separate user key event rate (users with a key event ÷ users) and session key event rate (sessions with a key event ÷ sessions). The denominators differ; state which one you report.