Same here. I use Chrome most of the time. I think this is something with how they have AAC set up. I don't think the non-forum side of the house supports the blue theme. I'm also guessing that the logged-in status is maintained by two different cookies for the two sides of the house.I stay in the blue theme, until I click on something in the top toolbar. Then, I switch to orange, and it asks me to log in again. Almost always the click was a mistake but if I click on Forums | Latest, I’m back on the New Posts page, in the blue theme and logged in.
My understanding is that Chrome is currently considered the most secure of the main browsers (which is a separate issue from ad tracking), but all of the main browsers are moving in the same direction in this regard.