In AOT `Expression.Lambda.Compile` method is implemented via an interpreter. So it does work, but it's relatively slow. Additionally it's not fully NativeAOT compatible yet.

There are two places where it's used in the source code:
* `ExceptionProcessor` uses it to access `Marshal.GetExceptionPointers` method which is not part of netstandard API. So in this case simply ifdef and on net6.0+ access the method directly (as it's visible in the net6.0 APIs) and fallback to the Expression.Lambda solution on down-level platforms. Since AOT/trimming is net6.0+ this fixes the problem.
* `ActivityInstrumentationHelper` uses it to access two setters on the `Activity` class which are internal. Using reflection and then `CreateDelegate` will provide basically the same performance (a delegate which directly calls the setter) without a need for `Expression.Lambda` - so the code is simpler. Since the reflection is statically analyzable (all types are known, the property names are known) this code is fully trim and AOT compatible.

There's no impact on warning count because the .NET 7 ASP.NET has Linq.Expression dependency as well. On .NET 8 though this removes all warnings from Linq.Expressions.