1、修改代码

lib/widget/my_app_bar.dart

@@ -16,7 +16,7 @@ class MyPageAppBar extends StatelessWidget implements PreferredSizeWidget {
     Key? key,
     this.title,
     this.backgroundColor,
-    this.foregroundColor = Colors.white,
+    this.foregroundColor,
     this.showBack = true,
     this.primary = true,
     this.onBack,