When it comes to deciding whether some clauses are predatory or not, we should rely on our judgement and experience, as well online gambling best practices.
The Terms and Conditions (T&Cs) should be written clearly so that they are easily and exactly understood by players. The entire system should be set up in a way that doesn't allow players to break the T&Cs unknowingly. All rules should be listed in one place (in the T&Cs), and they should not be unfair and/or predatory
Every single rule that players are required to follow should be stated in the casino's general T&Cs or in the Bonus T&Cs of each bonus. The casino should never try to apply rules that are not stated publicly, as players have no way of knowing about them.
What's more, all rules should be in line with fair play. Most players don't read the T&Cs before creating an account, so they will not notice a predatory rule by themselves. Casinos should help them gamble safely by only implementing fair rules, and should make sure the T&Cs are simple and easy to follow. Casinos should also avoid making up rules that can be misused against players who haven't done anything wrong.
A fair environment is good for casino business too. It is in the casino's interests to retain players and keep them active. If players experience an unfair approach towards them, they will no longer play on the casino website. And if the word about bad player experience spreads, players could register in other casinos instead.