Thanks! I never look at my Desktop and so never noticed it. I deleted the original, moved backup today, and there is nothing on my Desktop about Relocated Items. That could be because I removed it, like an Apple smart link thing, or maybe it was never there - dunno.
IMO, if they're going to do something this drastic, they should at least have a one-time large pop-up box after the upgrade explaining that they moved things that were formerly in root, and wait for a user to confirm that they read the notice.
That would be unnecessary for almost every single last macOS user, you are an outlier.
If you go against the grain or the way the OS is built and explicitly disable SIP and do things the OS would normally not allow, you are expected to understand the OS enough to know where things have disappeared to when they disappear.
I don't think Apple should protect the very small minority from themselves.
IMO, if they're going to do something this drastic, they should at least have a one-time large pop-up box after the upgrade explaining that they moved things that were formerly in root, and wait for a user to confirm that they read the notice.