On the desktop site when not logged in, there is a “Member Login” link at the top of the page. On the mobile site, the “Member Login” link is somewhat hidden within the hamburger menu and at the bottom of the page.
When logged in on the desktop, the “logout” link is in the “Account” drop-down at the top of the page. On mobile, the “logout” link in in the hamburger menu.
While this is a locationally inconsistent presentation of a pretty fundamental function, and it would be nice if login/logout were handled more similarly regardless of desktop or mobile sites, once learned this is not a terrible inconvenience IMO.
What I DO find to be a big annoyance is the loss of how the old site displayed my username at the top of the page. This was an unmistakeable and immediate indicator of login status. Since the contents of forum listings can depend on login status, and we are routinely logged out after some period of time, I find it important to verify login status when visiting forums.