Top screenshot is from a regular instance of Firefox where I’m returning to LinkedIn after having signed out before. Bottom screenshot is from a private browsing session -- no cookies saved, so I guess I look like a new user to them.
The frustration emerged when I didn’t realize I was in a private browsing session and clicked the big blue button to sign in.
The big blue button on the right is apparently not always the “sign in” button. It is the “this is the button we want you to click” button.
Okay, yeah, what confuses me most is why they used different labels. If I had to take a guess (gun to my head), I’d say one is an earlier version that got stuck in some cache somewhere.