I had a somewhat related idea to this which was simply to track reference stability (i.e., is there any operation beyond freeing the data outright that will invalidate them).

A reference into a vector is unstable so you can only have 1 mut xor N read. A reference into an arena is stable so you can have all the muts you want, but they cannot be sent across threads.

Reference to object vs reference to contents is also related, you can safely have multiple mut references to the same object that cannot invalidate each other, even if they invalidate references to the contents.

This can be tracked with path analysis as employed by Hylo (Hylo only has second class references, but I mean the algorithm they use to track paths is applicable).