RTP is the game’s long-run average return; the house edge is what it keeps: 96%...

https://varimail.com/articles/does-session-timing-matter-in-online-casinos/

RTP is the game’s long-run average return; the house edge is what it keeps: 96% RTP = 4% house edge. Volatility shapes how wins and losses arrive. In a short session, results can differ sharply from the average, so don’t treat RTP as a promise.