Settlements have clauses usually that prevent the same litigation from happening again. Otherwise it’s an infinite money glitch where people keep suing the same company again and again once it’s proven they’re willing to settle.
For instance you buy a dishwasher that is faulty. There’s a class action settlement, but for you, the dishwasher ruined your apartment and the neighbors downstairs. You can opt out and sue directly even if there’s been a class settlement.