it's probably the "you only notice when it doesn't work" situation, but my experience with firefox on ram limit has been a lot about tabs forgetting the url in them

as in, I click "open in new tab", some time later I switch to them... only to get hit with "new tab", even though a moment ago it displayed tab name and I could right click -> bookmark to preemptively copy the address

Try the "Auto tab discard" extension. It allows me to have hundreds of tabs "open" and (in combination with Tree Style Tabs) largely blur the line between "browser sessions" and "bookmarks".