There is no such thing as a slot ‘having a higher hit rate on other casinos’ you had a bad run on Unibet and a good run on some other casino, it’s literally purely coincidental. It’s all in the players head.
Not that me saying this will effect it whatsoever because people have posted similar things for years and I imagine they will continue too, a simple bit of research can confirm this but people would rather immediately flock to review sites and forums to ‘warn’ other that a certain casino “has something wrong with the rtp because I did 100 spins and didn’t win £1,000,000” it’s laughable really.