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

https://wiki-byte.win/index.php/Why_Does_a_%E2%80%9C96%25_RTP%E2%80%9D_Game_Still_Have_a_House_Edge_at_All%3F

RTP is a long-run average, not a session promise: 96% RTP means a 4% house edge over time. Volatility describes how uneven wins and losses can be. In a short session, results can differ sharply from the average, and you can lose your stake.