Sometimes programs have hash tables which use object identity as key (i.e. pointer).

ASLR can cause corresponding objects in different runs of the program to have different pointers, and be ordered differently in an identity hash table.

A program producing some output which depends on this is not necessarily a bug, but becomes a reproducibility issue.

E.g. a compiler might output some object in which a symbol table is ordered by a pointer hash. The difference in order doesn't change the meaning/validity of the object file, but is is seen as the build not having reproduced exactly.