RTP and house edge describe the long-run maths, not a promise about one...
https://zulu-wiki.win/index.php/Is_%E2%80%9CExpected_Value%E2%80%9D_the_Same_as_%E2%80%9CMost_Likely_Outcome%E2%80%9D%3F
RTP and house edge describe the long-run maths, not a promise about one session: a 96% RTP means a 4% house edge on average over many plays