Good morning!
Auto logouts have been the topic of a lot of discussion, and are thought to be a bug if they happen under an hour after initial log-in. It's been reported to Moderation numerous times.
The bad news is that no one who responds here can give you an official answer to the issue. We are your fellow end users, not molds or Apple employees. Mods won't respond to your question in open forums BUT you can email them. Their email address is shown several times in the Terms of Use document we all agreed to follow when we sign up.
Apple Support Community Terms of Use
As for "timed" or "cross-session log-outs" (quitting the forums, then coming back), we could stay logged in between sessions when I first started here over 23 years ago. It lasted maybe 3-4 years after I joined. Whether that was changed due to bandwidth limitations, a software change, or security concerns is far beyond the knowledge of any of the volunteers here.