Nintendo has confirmed that it will end support for Facebook and Twitter logins starting October 25th.
As of 10/25/2022, it will no longer be possible to sign in to a Nintendo Account using a Facebook or Twitter account. We apologize for any inconvenience.
More info on signing in from 10/25/2022:https://t.co/hxcwFP1O9s
— Nintendo of America (@NintendoAmerica) September 20, 2022
At that time, you’ll only be able to sign in using your Nintendo account or through a linked Apple/Google account. Nintendo has a dedicated page for the discontinuation here.
Additionally, Nintendo has announced that it’s ceasing support for Nintendo 3DS and Wii U image sharing to Facebook and Twitter. This will also take place on October 25th.