We just released an update which changes how we handle SSO, a full description of the changes will be posted in c/changelogs once the update is stable.
Please use this thread to notify of any issues with things like being logged out, being redirected to the old domain, etc. If you have a bug report, please also include what browser (ex. "Chrome") and version (ex. "89.0.4389.90") you're using, and whether you're using any privacy blocking extensions.
If you do get "logged out", it may not be as it appears. There's two options: for some browsers, you can wait a few seconds and you'll be automatically logged back in. If you aren't, then you can click the sign in button, and you may be immediately logged back in without having to re-enter any details. This would be the intended behavior for some privacy focused browsers and extensions, as well as some old browsers.
I think there's quite a few issues from scaling and caching as well as the anti-DDOS.
It seems like it expires pretty quickly. After some time idle it takes a long time to load the first page. It could be linked to restoring an account cache or the DDOS protection verifying but I can only speculate. Also the CRSF especially with multiple tags might have issues.
Because of caching sometimes comments can take some time to appear and editing also doesn't always apply I think (some eventual consistency perhaps and broken out of sync clocks or TZ).
The logged out but not logged out thing for me most reliably disappears when strangely I delete all the cookies from the Application tab in dev tools.
The delay at the start of a session (or every 60 minutes after a session began) is a flaw with our old SSO process, which this update addresses. The "logged out but not logged out" issue should be resolved with this update, too.