Updated May 25, 2022:
The Facebook login issue has been addressed.

Players who use Facebook as their main access to Sky should be able to log in normally. Thank you for your patience!

Going forward, we recommend adding a second login method to your account so that, in the event of a similar issue, you’ll still be able to access Sky.
We are aware that some players logging in through Facebook are having difficulties accessing Sky and are investigating the cause of the issue.

Thank you for your patience