Method groups are a group of methods with the same name on a type but with different parameters (overloads).
Prior to C# 13 the type resolution was quite basic and you often needed to cast the method group in order to get the correct method.
C# 13 improves this by pruning inapplicable overloads earlier so the compiler is more likely to identify the correct method without additional casts.
Code
C#
// The compiler can now determine the correct overload
Task.Run(LocalFunction);
void LocalFunction() { }C#
// Ambiguous between Action and Func<Task> overloads
// Required an explicit cast to resolve
Task.Run((Action)LocalFunction);
void LocalFunction() { }