We offer an option protecting players who are disconnected before a Sit & Go starts. The system will unregister players from specific Sit & Gos if they're disconnected for longer than a specified amount of time. The time they'll need to be disconnected will depend on the specific Sit & Go and will be configured per tournament.
The goal of the feature is to help prevent players who register and then get disconnected from being blinded out when they're no longer able to connect to play.
You can turn off this option if you want by going to:
Settings → Gameplay → Advanced
In the Tournaments / Sit & Go section, check No automated unregistering for Sit & Go tournaments and finish by selecting Apply Changes.