`IDE0241` is not reported when found attribute

[DoctorKrolic]

Version Used:
VS 2022 v17.5 Preview 1

Steps to Reproduce:
Setup project with nullable enabled in .csproj

#nullable disable

//[Flags]
enum MyEnum
{

}

Observer thta IDE0241 is reported.
Uncomment //[Flags]

Diagnostic Id:
IDE0241

Expected Behavior:
IDE0241 is still reported because attributes don't create nullability issues

Actual Behavior:
IDE0241 is not reported