Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
My son has a family-link managed google account and gets this message now for this past few weeks when trying to login into Scoutbook from a browser. Interestingly, it appears that the Scouting app still works, but that may be cached credentials. This is consistent across browsers. Sometimes when logging in the Google icon doesn’t even show up as an option when trying to authenticate. Does this have anything to do with the change earlier this month that enabled me to login without having to click the login button?
The content permissions on youtube have changed. When I look at 3rd party apps I see the scouting.org app listed, but on the scoutbook.scouting.org is not listed. This is true of both my son’s account and mine.