https://learn.microsoft.com/en-us/dotnet/api/system.linq.expressions.idynamicexpression.delegatetype?view=netframework-4.8.1&viewFallbackFrom=net-9.0
IDynamicExpression.DelegateType Property (System.Linq.Expressions) | Microsoft Learn
Gets the delegate type used by the CallSite, which is the type of the rules used in the dynamic expression's polymorphic inline cache.
property systemlinqexpressionsmicrosoftlearn