In Firebase A/B testing setup you can define a target group for a test, e.g. by defining some user properties or language settings.
If, after the user has passed the activation event (if one was defined), one of those properties changes for them so that they don't match the target group criteria anymore, will they also leave the A/B test and not included in result data anymore?
And if they leave the A/B test, will they still keep their test value via RemoteConfig?
Once a user has entered an experiment, they will continue to be part of that experiment up until the experiment has ended. This is enforced to maintain the validity of the experiment.