Using Color() in background modifier in SwiftUI does not work with Xcode 15.3

I had this code working properly in Xcode 17.0.1, with macOS target as 12.4

struct SyntheseView: View {
    @AppStorage("isDarkMode") var isDarkMode = false

       // more declarations ………

    var body: some View {
        
        VStack {   
            ZStack {
                // code …………………
            }
            .frame(width: 500, height: 300)
            .background(isDarkMode ? Color(red: 0, green: 0, blue: 120/255) : Color(red: 1, green: 1, blue: 186/255))
        }   // VStack

In Xcode 15.3, I get the error The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions

If I comment out the background modifier, no issue.

I converted all parameters in Color to Double without success

If I replace by a fixed color as

.background(.blue)

No error.

Even the simple

            .background(Color(red: 0.0, green: 0.0, blue: 0.5))

causes the error.

But:

.background(isDarkMode ? .blue : .red)

does work.

I tried to define the Colors as static color extensions to no avail.

Another bizarre point is that a similar pattern works OK for another View.

Did something change in Xcode 17.3 ?