IQuerable Inherits IEnumerable and extends it with functionality to lessen the memory loaded when querying a collection (typically when reading from a database). Using IEnumerable can increase memory usage significantly compared to IQuerable.
Not every C# developer knows the difference, in my region of the world it’s an infamous mistake and is often the first thing you look for when tasked with improving bottlenecks in C# backends. On the flip-side, using IQuerable isn’t very efficient if what you wanted was to work on in memory collections.
There is an equally infamous somewhat related issue in Python with list vs generators. Especially common when non Python developers work with Python.
The closest thing coming to mind to me is mixing up IEnumerable and IEnumerator when trying to define a coroutine.