Images that are not subject to animation will also flash.

When you run the following SwiftUI code, images unrelated to animation will flicker.

import SwiftUI

struct TestAnimationView: View {
  @State private var effectFlg = false
  private let imageName = "image1"
  @State var rotationDegrees = 0.0
  
  var body: some View {
    VStack() {
      Text("Rectangle")
      Rectangle()
          .foregroundColor(.blue)
          .frame(width: 100, height: 100)
          .padding(.bottom, 30)
      
      Text("PNG Image")
      if let _imageName = Bundle.main.path(forResource: imageName, ofType: "png") {
        Image(uiImage: UIImage(contentsOfFile: _imageName)!)
          .resizable()
          .frame(width: 100, height: 100)
          .padding(.bottom, 30)
      }
      

      Text("PNG Image")
      if let _imageName = Bundle.main.path(forResource: imageName, ofType: "png") {
        Image(uiImage: UIImage(contentsOfFile: _imageName)!)
          .resizable()
          .frame(width: 100, height: 100)
//          .scaleEffect(self.effectFlg ? 1 : 0.8)
          .rotationEffect(.degrees(self.rotationDegrees))
      }
      
      Spacer()
      Button("Start Animation") {
        withAnimation(.default.repeatForever().speed(0.5)) {
          if self.effectFlg {
            rotationDegrees = 0.0
          } else {
            rotationDegrees = 360.0
          }

          self.effectFlg.toggle()
        }
      }
    }
  }
}