Follow-up: I am seeing similar behavior today on Apple Business Connect. (I go through the login process, but after about 30 seconds, I am booted out and asked to re-log in.
Seeing this in Version 0.99.132.2-rc (WebKit 621.1.2.111.4) (April 8, 2025) as well
I'm wondering if there's some bug in keeping the logged-in credentials available to appropriate webpage?—It does seem particular to websites that have progressive disclosure login processes (e.g. type email first, only see password field after typing email, only see one-time-code entry after submitting password)