The new update is version G950USQU1AQJ8 for the Galaxy S8 and G955USQU1AQJ8 for the Galaxy S8+. Galaxy S8 owners can expect their update to weigh in at 155.45MB, while Galaxy S8+ owners will be downloading a 151.98MB file.
Included with this new update is the October 2017 security patches as well as some unspecified “system improvements.”
If you’ve got a T-Mobile Galaxy S8 or Galaxy S8+ and haven’t yet gotten this update, you can check for it by going into Settings > Software update > Download updates manually > OK > Start.
Thanks, Jose and Chaz!