Passes with just SkRenderer, so probably a SkDDL specific issue. Same with CaptureScreenshotTest.TransparentScreenshots.

$ out/linux_rel/content_browsertests  --enable-features=VizDisplayCompositor,UseSkiaRenderer,UseSkiaDeferredDisplayList --gtest_filter=CaptureScreenshotTest.SetDefaultBackgroundColorOverride
IMPORTANT DEBUGGING NOTE: each test is run inside its own process.
For debugging a test inside a debugger, use the
--gtest_filter=<your_test_name> flag along with either
--single_process (to run the test in one launcher/browser process) or
--single-process (to do the above, and also run Chrome in single-process mode).
Using sharding settings from environment. This is shard 0/1
Using 1 parallel jobs.
Note: Google Test filter = CaptureScreenshotTest.SetDefaultBackgroundColorOverride
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from CaptureScreenshotTest, where TypeParam = 
[ RUN      ] CaptureScreenshotTest.SetDefaultBackgroundColorOverride

DevTools listening on ws://127.0.0.1:35505/devtools/browser/10754978-11aa-446f-8009-cdf71b4bd6d4
[145524:145568:1204/163456.349744:ERROR:skia_output_surface_impl.cc(260)] Not implemented reached in virtual void viz::SkiaOutputSurfaceImpl::EnsureBackbuffer()
[145503:145503:1204/163456.701524:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,0): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701610:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,1): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701627:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,2): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701641:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,3): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701654:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,4): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701667:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,5): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701681:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,6): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701694:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,7): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701707:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,8): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.701720:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (0,9): expected ff0000ff actual ffffffff
[145503:145503:1204/163456.719154:ERROR:devtools_protocol_browsertest.cc(374)] Number of pixel with an error: 32322
[145503:145503:1204/163456.719174:ERROR:devtools_protocol_browsertest.cc(375)] Error Bounding Box : 0,0 800x600
../../content/browser/devtools/protocol/devtools_protocol_browsertest.cc:434: Failure
Value of: MatchesBitmap(expected_bitmap, *result_bitmap, matching_mask, device_scale_factor, error_limit)
  Actual: false
Expected: true
Stack trace:
#0 0x562e041b37dc testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop()
#1 0x562e041b31b9 testing::internal::AssertHelper::operator=()
#2 0x562e03adc4ed content::CaptureScreenshotTest::CaptureScreenshotAndCompareTo()
#3 0x562e03add461 content::CaptureScreenshotTest_SetDefaultBackgroundColorOverride_Test::RunTestOnMainThread()
#4 0x562e042fac07 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#5 0x562e0435aa26 content::ShellBrowserMainParts::PreMainMessageLoopRun()
#6 0x7f633a364fe5 content::BrowserMainLoop::PreMainMessageLoopRun()
#7 0x7f633a8a5495 content::StartupTaskRunner::RunAllTasksNow()
#8 0x7f633a363d09 content::BrowserMainLoop::CreateStartupTasks()
#9 0x7f633a3678a6 content::BrowserMainRunnerImpl::Initialize()
#10 0x562e043584da ShellBrowserMain()
#11 0x562e04350b90 content::ShellMainDelegate::RunProcess()
#12 0x7f633aebff2b content::ContentMainRunnerImpl::RunServiceManager()
#13 0x7f633aebfdf6 content::ContentMainRunnerImpl::Run()
#14 0x7f632f46247a service_manager::Main()
#15 0x7f633aebe0f1 content::ContentMain()
#16 0x562e042fa79e content::BrowserTestBase::SetUp()

[145503:145503:1204/163456.882476:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,3): expected ffffffff actual ffe2e3e4
[145503:145503:1204/163456.882523:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,4): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882537:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,5): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882552:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,6): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882565:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,7): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882579:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,8): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882593:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,9): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882606:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,10): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882619:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,11): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.882632:ERROR:devtools_protocol_browsertest.cc(364)] Pixel (2,12): expected ffffffff actual ffdedfe0
[145503:145503:1204/163456.904712:ERROR:devtools_protocol_browsertest.cc(374)] Number of pixel with an error: 450621
[145503:145503:1204/163456.904737:ERROR:devtools_protocol_browsertest.cc(375)] Error Bounding Box : 2,2 798x598
../../content/browser/devtools/protocol/devtools_protocol_browsertest.cc:434: Failure
Value of: MatchesBitmap(expected_bitmap, *result_bitmap, matching_mask, device_scale_factor, error_limit)
  Actual: false
Expected: true
Stack trace:
#0 0x562e041b37dc testing::internal::UnitTestImpl::CurrentOsStackTraceExceptTop()
#1 0x562e041b31b9 testing::internal::AssertHelper::operator=()
#2 0x562e03adc4ed content::CaptureScreenshotTest::CaptureScreenshotAndCompareTo()
#3 0x562e03add557 content::CaptureScreenshotTest_SetDefaultBackgroundColorOverride_Test::RunTestOnMainThread()
#4 0x562e042fac07 content::BrowserTestBase::ProxyRunTestOnMainThreadLoop()
#5 0x562e0435aa26 content::ShellBrowserMainParts::PreMainMessageLoopRun()
#6 0x7f633a364fe5 content::BrowserMainLoop::PreMainMessageLoopRun()
#7 0x7f633a8a5495 content::StartupTaskRunner::RunAllTasksNow()
#8 0x7f633a363d09 content::BrowserMainLoop::CreateStartupTasks()
#9 0x7f633a3678a6 content::BrowserMainRunnerImpl::Initialize()
#10 0x562e043584da ShellBrowserMain()
#11 0x562e04350b90 content::ShellMainDelegate::RunProcess()
#12 0x7f633aebff2b content::ContentMainRunnerImpl::RunServiceManager()
#13 0x7f633aebfdf6 content::ContentMainRunnerImpl::Run()
#14 0x7f632f46247a service_manager::Main()
#15 0x7f633aebe0f1 content::ContentMain()
#16 0x562e042fa79e content::BrowserTestBase::SetUp()

[145503:145513:1204/163456.964994:WARNING:discardable_shared_memory_manager.cc(410)] Some MojoDiscardableSharedMemoryManagerImpls are still alive. They will be leaked.
[145503:145588:1204/163456.980335:WARNING:internal_linux.cc(64)] Failed to read /proc/145524/stat
[  FAILED  ] CaptureScreenshotTest.SetDefaultBackgroundColorOverride, where TypeParam =  and GetParam() =  (1976 ms)
[----------] 1 test from CaptureScreenshotTest (1976 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (1976 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] CaptureScreenshotTest.SetDefaultBackgroundColorOverride, where TypeParam =  and GetParam() = 

 1 FAILED TEST
[1204/163457.703360:ERROR:kill_posix.cc(84)] Unable to terminate process group 145503: No such process (3)
[1/1] CaptureScreenshotTest.SetDefaultBackgroundColorOverride (2621 ms)
1 test failed:
    CaptureScreenshotTest.SetDefaultBackgroundColorOverride (../../content/browser/devtools/protocol/devtools_protocol_browsertest.cc:579)