What SwiftUI's ColorPicker should have been.

ColorPicker.swift

import SwiftUI

@available(iOS 14.0, *)
public struct ColorPickerWithoutLabel: UIViewRepresentable {
    @Binding var selection: Color
    var supportsAlpha: Bool = true
    
    public init(selection: Binding<Color>, supportsAlpha: Bool = true) {
        self._selection = selection
        self.supportsAlpha = supportsAlpha
    }
    
    
    public func makeUIView(context: Context) -> UIColorWell {
        let well = UIColorWell()
        well.supportsAlpha = supportsAlpha
        return well
    }
    
    public func updateUIView(_ uiView: UIColorWell, context: Context) {
        uiView.selectedColor = UIColor(selection)
    }
}

extension View {
    @available(iOS 14.0, *)
    public func colorPickerSheet(isPresented: Binding<Bool>, selection: Binding<Color>, supportsAlpha: Bool = true, title: String? = nil) -> some View {
        self.background(ColorPickerSheet(isPresented: isPresented, selection: selection, supportsAlpha: supportsAlpha, title: title))
    }
}

@available(iOS 14.0, *)
private struct ColorPickerSheet: UIViewRepresentable {
    @Binding var isPresented: Bool
    @Binding var selection: Color
    var supportsAlpha: Bool
    var title: String?
    
    func makeCoordinator() -> Coordinator {
        Coordinator(selection: $selection, isPresented: $isPresented)
    }
    
    class Coordinator: NSObject, UIColorPickerViewControllerDelegate, UIAdaptivePresentationControllerDelegate {
        @Binding var selection: Color
        @Binding var isPresented: Bool
        var didPresent = false
        
        init(selection: Binding<Color>, isPresented: Binding<Bool>) {
            self._selection = selection
            self._isPresented = isPresented
        }
        
        func colorPickerViewControllerDidSelectColor(_ viewController: UIColorPickerViewController) {
            selection = Color(viewController.selectedColor)
        }
        func colorPickerViewControllerDidFinish(_ viewController: UIColorPickerViewController) {
            isPresented = false
            didPresent = false
        }
        func presentationControllerDidDismiss(_ presentationController: UIPresentationController) {
            isPresented = false
            didPresent = false
        }
    }

    func getTopViewController(from view: UIView) -> UIViewController? {
        guard var top = view.window?.rootViewController else {
            return nil
        }
        while let next = top.presentedViewController {
            top = next
        }
        return top
    }
    
    func makeUIView(context: Context) -> UIView {
        let view = UIView()
        view.isHidden = true
        return view
    }
    
    func updateUIView(_ uiView: UIView, context: Context) {
        if isPresented && !context.coordinator.didPresent {
            let modal = UIColorPickerViewController()
            modal.selectedColor = UIColor(selection)
            modal.supportsAlpha = supportsAlpha
            modal.title = title
            modal.delegate = context.coordinator
            modal.presentationController?.delegate = context.coordinator
            let top = getTopViewController(from: uiView)
            top?.present(modal, animated: true)
            context.coordinator.didPresent = true
        }
    }
}

Turns out, using your struct ColorPickerWithoutLabel broke my code. I believe this is due to the fact that yours only supports Color types, while Swift's also supports CGColors :

public struct ColorPicker<Label> : View where Label : View {

    /// Creates an instance that selects a color.
    ///
    /// - Parameters:
    ///     - selection: A ``Binding`` to the variable that displays the
    ///       selected ``Color``.
    ///     - supportsOpacity: A Boolean value that indicates whether the color
    ///       picker allows adjusting the selected color's opacity; the default
    ///       is `true`.
    ///     - label: A view that describes the use of the selected color.
    ///        The system color picker UI sets it's title using the text from
    ///        this view.
    ///
    public init(selection: Binding<Color>, supportsOpacity: Bool = true, @ViewBuilder label: () -> Label)

    /// Creates an instance that selects a color.
    ///
    /// - Parameters:
    ///     - selection: A ``Binding`` to the variable that displays the
    ///       selected ``CGColor``.
    ///     - supportsOpacity: A Boolean value that indicates whether the color
    ///       picker allows adjusting the selected color's opacity; the default
    ///       is `true`.
    ///     - label: A view that describes the use of the selected color.
    ///        The system color picker UI sets it's title using the text from
    ///        this view.
    ///
    public init(selection: Binding<CGColor>, supportsOpacity: Bool = true, @ViewBuilder label: () -> Label)

    /// The content and behavior of the view.
    ///
    /// When you implement a custom view, you must implement a computed
    /// `body` property to provide the content for your view. Return a view
    /// that's composed of built-in views that SwiftUI provides, plus other
    /// composite views that you've already defined:
    ///
    ///     struct MyView: View {
    ///         var body: some View {
    ///             Text("Hello, World!")
    ///         }
    ///     }
    ///
    /// For more information about composing views and a view hierarchy,
    /// see <doc:Declaring-a-Custom-View>.
    @MainActor public var body: some View { get }

    /// The type of view representing the body of this view.
    ///
    /// When you create a custom view, Swift infers this type from your
    /// implementation of the required ``View/body-swift.property`` property.
    public typealias Body = some View
}

Thank you so much!