Passing an identity function to Select() is redundant CS-P1015
Performance
Major
The Select() method from System.Linq transforms an IEnumerable<T>'s elements based on the lambda specified. An identity function is a function that returns the same element unchanged that was passed as its argument. Since such a function does nothing useful, passing it to Select() does not modify the elements and is just a redundant expression. It is recommended that you drop such redundant expressions.
Bad Practice
var filtered = elements.Select(x => x).Where(x % 4 == 0);
Recommended
var filtered = elements.Where(x % 4 == 0);