This manifests as lots on concurrent failures displayed in Treeherder. Luckily, Treeherder allows you to pin up to 500 jobs at one time, greatly speeding up the starring process.
If the failure is pervasive, i.e. platform-independent, you can use Treeherder to show unclassified failures. Pin all the failures for a single push, and then mark them as "fixed by commit." so repeat Repeat until it's done for that single push, then move on to the next push.
If only a subset of platforms are affected, i.e. all on one build target or test suites, you can filter on the top right of the Treeherder interface with the search field and also filter for the job name (substring) which is shown at the bottom left if you select a job