One example I've reported in issue 900225 - bot page shows "angle_end2end_tests" failure, but the build page shows something else, for example "bot_update" failure.

Another example is https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20FYI%20Release%20%28AMD%29/3226
It ends in gpu_process_launch_tests being purple, but https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20FYI%20Release%20(AMD) shows webgl2_conformance_tests failing for that build.