Rule S2325 warns when members can be static as they do not access instance data.
With C#14 a new way of defining extensions has been introduced. The rule does not recognize its syntax yet (apparently). I assume that the team is working on the new language features, but you might have missed this.
public static class Extensions
{
extension(int number)
{
public bool IsEven => number % 2 == 0; // FP, number is instance data.
public bool IsOdd() => number % 2 != 0; // FP, number is instance data.
}
}
Reported by SonarAnalyzer.CSharp v10.15.0.120848