RTP estimates returns over many plays: 96% RTP = 4% house edge, not a promise...

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

RTP estimates returns over many plays: 96% RTP = 4% house edge, not a promise for one session. Volatility shapes how wins and losses arrive—steadily or in larger swings. Short runs can differ sharply from the average, and you can lose your stake.