[Dylan16807]

Except this memory is not being intentionally used as a cache/buffer.

Rust attempts to keep the vector capacity in a range for that purpose, and failed to do so here.

No matter what, it's a bug. So none of those possible justifications fit, because it's a bug.

For the database analogy, I would call it a connection leak if the number of idle connections greatly exceeded the amount that had ever been simultaneously busy and they weren't actually getting reused.