Yep, each provider and game have different maximum multipliers, RTP, winning way etc. Popularity doesn't mean it always the best worthy game, but sometime people play on there since they're influenced with a streamer who play those game and won huge multipliers. I don't mind to play in new game, but I still stick with the trusted and known provider.
In addition, each game provider can bring to another thing, restricted area and available area for users to play their games. If you want to play on a casino, you must use Search (Ctrl+F) to scan their Terms of Service and find their terms on restricted areas in general and for the game you are interested in to play.
Actually I'm surprised how those games become favorited on Fairspin since in my own experience playing slots in other casino, I don't see these games as the most popular. What I know is only the dog house megaways, wanted dead or a wild, and Aloha King Elvis.
It's questionable how the gate of olympus and sweet bonanza didn't appeared on the top 10 popular games.
Some games are common and more favorite than others. As a casino, they can collaborate with game providers and have price for package of different games from a provider. So favorite games will cover less favorite games in one package.
this list can be changed from time to time. we usually create a list of most popular games for the month based on two criteria: amount of players and amount of bets.