Tabs which get unloaded automatically mean that, when you switch to them, you get a long delay before you can view the tab again, and worse: it makes a new HTTP request, so if you were viewing a Confluence page or something, you will be tracked for reading the page again. So it's not a feature I've ever liked, but I like that Firefox will only unload a tab if it thinks it will crash due to low memory situations because that has never been an issue for me before. It's the main reason I like to use Firefox, Chromium based browsers are waaay too aggressive with this in my experience.