I've seen this across a bunch of builds, but https://ci.chromium.org/buildbot/tryserver.chromium.linux/linux_chromium_asan_rel_ng/520128 is an example.

"Upload to test-results [interactive_ui_tests (with patch)]" takes 11 seconds, as displayed on the above page. However, if you look at the step log itself, in https://logs.chromium.org/v/?s=chromium%2Fbb%2Ftryserver.chromium.linux%2Flinux_chromium_asan_rel_ng%2F520128%2F%2B%2Frecipes%2Fsteps%2FUpload_to_test-results__interactive_ui_tests__with_patch__%2F0%2Fstdout, it takes only 7 seconds internally. This is confirmed by looking at the annotation stream (I couldn't figure out how to link this, but `logdog cat -timestamps utc chromium/bb/tryserver.chromium.linux/linux_chromium_asan_rel_ng/520128/+/recipes/annotations` seems to work for me). According to that, the step takes 7 seconds. In addition, the step before the upload ends a few milliseconds before the upload step starts, and the step after starts a few milliseconds after the upload ends.

We seem to be apparently losing 4 seconds somewhere. Or, milo is using wrong data. Either way, something seems wrong here.