I've heard that MSVC does (did?) that, but if so that's an MSVC problem. gcc and clang don't do that.
https://godbolt.org/z/nasoWeq5M
WDYM? Vector is an abstraction over dynamically sized arrays so sure it does use heap to store its elements.
WDYM? Vector is an abstraction over dynamically sized arrays so sure it does use heap to store its elements.