There is a bug in ChromiumTryFlake in how it handles without patch logic:
https://cs.chromium.org/chromium/infra/appengine/chromium_try_flakes/handlers/flake_issues.py?l=834

The way ChromiumTryFlake handles it is that for any given test step, if both with patch and without patch steps fail, then this test step is completely ignored, this is not correct, for example:

fail build:
  dummy test (with patch): fails t1, t2, t3
  dummy test (without patch): fails t3

success build:
  dummy test (with patch): success

In this case, it tells us t3 is unrelated to the patch (likely a consistent failure). But t1 and t2 should be deemed as flakes.