Network Image Mock not same color between first test and seconde, third,

first image : enter image description here

second image : enter image description here

thrid image : enter image description here

example my code:

    await mockNetworkImagesFor(() async {
      final testPage = CircleAvatar(
        radius: Sizes.profilePictureRadius,
        backgroundImage: NetworkImage(
          HttpConstants.defaultAvatarUrl,
        ),
      );

      await TestUtils.pumpWidget(tester, testPage);

      await expectLater(
          find.byType(Container), matchesGoldenFile('test_01.png'));
    });