We have had intermittent outages for three days in a row where Steam is suffering issues with Steam token authentication (Not the Steam API). This flow is mandatory for our game to work as our backend services are using Steamworks.
Issues have happened (Eastern Standard Time):
• between 7:00 and 9:00 on Thursday
• between 7:00 and 10:00 on Friday
• between 0:00 and 10:00 on Saturday
Steam are fully aware and since not many games are using this specific path, which meant few games were affected. Those were the main outage times.
We sincerely apologize for the inconvenience this may have caused you and wanted to make everyone sure that we are aware and working on it with Steam.
Updated: Steam just confirmed that this is now fixed and shouldn't happen again.