This right here is just a popular fallacy, his release clause was what it should, the amount of a release clause is not a random number you can choose like Lopera did with Denilson or Real have claimed to be with Ronaldo, it's the worth of a contract, if you want to be free of your contract you buy it, and the price is around the worth of said contract plus a compensation to the team for leaving them with the problem of finding a substitute for you (a set market value of the player).
You have two ways of doing that, either you set a reasonable fee with the club based on realistic expectations, or you dispute it and a judge has to decide what would be your real release clause. In the event of a player demanding to leave like Ney did this season it would cause more turmoil to have an unrealistic release clause and him having to bring it to a judge, it would be slower, create drama and probably the decission would come after the transfer window is closed, awful spot to be in.
That's why a lot of our players in the lower end of our wage table (Sergi Roberto, Umtiti, etc) have relatively low release clauses, because they have what the law would dictate in case they want to leave, not some Narnia-like number that wouldn't hold legally. And that's also why Tebas and La Liga fought the Qatar money as much as they could, it's not only about Barcelona and Neymar, 90% of the Spanish clubs can't compete in wages with EPL clubs and soon against Bundesliga too, their release clauses are going to be low enough that the set amount you can put is lower than their market value in a country that doesn't have release clauses, like France, England or Germany.
If Dembele had a proper release clause depending on his contract, he'd probably be cheaper than 100M, but as that doesn't exist in Germany, all the clubs of that league are going to be in a stronger position to sell their players than everyone in Spain bar Real and Barcelona