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

https://cashsexpertinsight.talesignal.com/posts/why-do-people-confuse-volatility-with-rtp

RTP is a long-run average, not a session promise: at 96% RTP, the house edge is 4%, or about £4 per £100 wagered over time. Volatility shapes how wins and losses arrive. In a short session, results can swing sharply either way.