I've been using the 'Full Screen for Google Tasks' extension on ChromeOS for a long time without any problems. After a reboot, I was no longer signed in (got the demo list of tasks), and signing in only got the 'The sign-in window has popped out' error (see attached screenshots).- I am using multi-login, but have in the past without problems.- I am able to see my tasks at https://calendar.google.com/calendar/u/0/r/tasks, so I believe I am authenticated.
I found the issue, I believe - this is 100% reproducible, with the setting of the 'third party cookies allowed' toggle. With third party cookies disallowed, I get this behavior repeatedly (see below), but with them enabled, it works without any problems, and I do not even have to log in.There are details about this in https://developers.google.com/privacy-sandbox/3pcd , and various news reports if you google 'third-party cookies chrome'. I was opted into this testing early.