std::allocator<T>::deallocate (3) - Linux Man Pages
void deallocate( T* p, std::size_t n );
Deallocates the storage referenced by the pointer p, which must be a pointer obtained by an earlier call to allocate().
The argument n must be equal to the first argument of the call to allocate() that originally produced p; otherwise, the behavior is undefined.
or ::operator_delete(void*, std::align_val_t)
(since C++17), but it is unspecified when and how it is called.
p - pointer obtained from allocate()
n - number of objects earlier passed to allocate()
allocate (public member function)
deallocate deallocates storage using the allocator