In this case, a sort of official news source would be the game provider's website.
RTP is not a thing anybody would willingly and officially lower. 🙂 It can vary across the casinos, based on the contry you come from, just an example.
Casinos should show slots's RTP so players can decide whether it's worth the try, a decent RTP starts at 96%.
Did you know that some game providers allow casinos to pick the RTP they prefer to provide to players?
Generaly, most players reffer to the lower RTP - Retur to player - when they feel, they have lost more that deposited.
Interested to learn how it works for slots?
Just an example:
"If a game RTP is 96%, it means that if you start with $1,000,000,000 and then play 1,000,000,000 rounds at $1 each, then you should end up with approximately $960,000,000 dollars."
Check out this guide.
Automatic translation: