Union/sum types are generally a good thing. Even Java added them. They tend to be worth “the madness”. Now the rest of all the crazy C# features might be a different question.
Do you mean the implicit nullable types? Now that you can make nullable explicit instead I really don’t have much issues with it. It is part of the type system, as it should, and you have null coalescing operators. Is it still problematic or are you dealing with older codebases where you cannot set the nullable pragma?
Given that they already made the billion dollar mistake, I find their handling for nulls the best possible thing they could do at this point. I’d hardly call it crazy — rather, it’s exceedingly pragmatic.