ViewBuilder supports only no more than 10 static views in one container… that’s a reason of your error
Just group them
Group {
TextField("Class 1-1", text: $class11)
TextField("Class 1-2", text: $class12)
TextField("Class 1-3", text: $class13)
TextField("Class 1-4", text: $class14)
TextField("Class 2-1", text: $class21)
TextField("Class 2-2", text: $class22)
TextField("Class 2-3", text: $class23)
TextField("Class 2-4", text: $class24)
}