Tests seem to pass only when running one at a time

We are running tests 5 at a time using `asyncCaptureLimit: 5`. This is causing tests to fail and fail almost randomly (not the same tests failing every time). The tests show that there are like 5-10 pixels off on the pages. However, with seeing this in the browser and just running the tests, nothing has clearly changed. However, when running the tests 1 by 1 manually, the tests pass. Seems like more of the tests pass when I set asyncCaptureLimit to 2. Any idea why this is happening? It is very inconsistent and honestly a real headache for our dev team to the point where we assume the regression tests will always fail because on the inconsistency and reliability of our tests.