IIRC, it should create an alias on your Desktop called Relocated Items or something similar to them after the upgrade that pointed at it.
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.
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.