yes, there is: GC will not use stack allocation and it will add another layer of memory management resulting in significant memory overhead (runtime overhead)

Of course they do. For example C#, D, Nim etc all use stack allocation with their GC.

Not to mention Rust also allocates dynamic objects on the heap. So not sure what is your point.

The language may allow it, but it's not GC managed then.

My point is runtime overhead. In C# structs and their refs (including a simple borrow checker to detect invalid ref use) were introduced to escape GC management und reduce it's runtime impact on the programs