FWIW If you are using Github Copilot Edit/Agent mode - you may have more luck with other plugins. Until recently, Claude 3.5 Sonnet worked really well with C# and required relatively few extra commands to stay consistent to "newest tersest" style. But then, from my understanding, there was a big change in how Copilot extension handles attached context alongside changes around what I presume prompt and fine-tuning which resulted in severe degradation of the output quality. Hell, even attaching context data does not properly work 1 out of 3 times. But at least Gemini 2.5 Pro can write test semi-competently, but I still can't fathom how did the manage to make it so much worse!