Hello, I now believe this to be a manifestation of [bug #61463: private does not suppress inheritance on exported target specific variables](https://savannah.gnu.org/bugs/index.php?61463) which I now discover has been fixed in [GNU Make 4.4.1 released!](https://lists.gnu.org/archive/html/info-gnu/2023-02/msg00011.html) with the following release note:
* Previously target-specific variables would inherit their "export" capability from parent target-specific variables even if they were marked private. Now private parent target-specific variables have no affect. For more details see https://savannah.gnu.org/bugs/index.php?61463 I will get the newest version installed and confirm...
