Version Used: 4.12.0, lab.razor.fyi reproduces it on 5.0.0-1.25357.1 as well

Steps to Reproduce:
Run the code and/or inspect the generated code:
https://lab.razor.fyi/#xZLBSgMxEIYRLWhO4hOMi4cEZKlXt90SCwrSSlHQYik13aZrZDepyWyx1H0EX0bw4tmzb-C7yGotWlBvepx__p__YxjyVCKkZU1sRepHbuOhlDmlYziZOJRpQD5P_rEcJjJCZfTCoqH0dUDIWFgQUAXa4bwLI2FF6sChVTrudEEwqIYwzQujUQPg39qmOSF1o51JpH9mFcqG0pJS07-SEdaY8JsSL83AP5DYKtISpXWUdcrdQqpnDk3KEa3qZygrbxZurZjMtZAyqNXAOzIgPjSPBT-24mQkzZDObsWKpncM6lUqTaF0uBXGvR6_Lfd2vG2ge0oPlI73ExE7pjT6TXFzKpJMss1_AW9_QeZ_jzjK-omKIEqEc9AmUwIwk35_h3whzjnswrwyIIfLNtPna6vPL4_3d8P1lYulVw

You can see that the compiler generated symbols that are easily accessible with reflection are missing ParamArrayAttribute. The same behaviour is also noticeable for ParamCollectionAttribute.

Expected Behavior:
ParamArrayAttribute and ParamCollectionAttribute are preserved so that they can be used for example by frameworks that utilise ASP.NET Core minimal API-like APIs.

Actual Behavior:
ParamArrayAttribute and ParamCollectionAttribute are lost.