See the Experimentation Workflow for general information about ending experiments
Feature state changes
If there is a problem and I need to abort the experiment and rollout, will cancelling the experiment and rollout revert the feature flags to their pre-experiment and pre-rollout states (i.e. feature is disabled) for all users enrolled so far?
Ending means Nimbus stops applying the change, so users will go back to whatever state they would have without the experiment or rollout applied. If you have a complex feature - you can verify by asking QA to test that scenario before release as well.