User has working software. User updates operating system. User has broken software.

That's a problem for the party trying to sell operating system updates.

The software was fundamentally broken before the OS update. It was working by pure random chance with undefined behaviour. It’s a C++ issue, not an OS issue. The same code compiled for another OS would have different random results.

While this is technically correct that doesn’t get the customer to put the blame where it belongs.

The problem is hostile pedants who neglect to consider the human element.

Not a C++ issue, but a sloppy developer issue.