RTP is a long-run average, not a session promise: 96% RTP means a 4% house edge...

https://wiki-mixer.win/index.php/Is_Casino_Gambling_Ever_a_Good_Investment_Idea%3F

RTP is a long-run average, not a session promise: 96% RTP means a 4% house edge over time. Volatility affects how uneven results can be. In a short session, swings can leave you well ahead of or behind that average.