If you can reproduce, please provide request ID headers, especially for the request that produced the error.

We have recently introduced a sessionJwt cookie (in October I think for normal sessions, in the last few days for bot password sessions) which can invalidate the session if it e.g. doesn't match the user ID. So one option is that something is going wrong with that.

Data point - earlier today I tried to log-in to outreach wiki and the initial log-in didn't work - the second log-in page I was given had a captcha. That time, when I entered the same u/p as well as the captcha, it worked.

Probably unrelated unless you saw the specific error message about cookies? Someone must have made a bunch of failed logins from your IP.

@matmarex moving to needs refinement - can you try to reproduce this?