The 'allDuplicates' canceling mode should become your favorite canceling mode. It is much more resistant to queueing problems in case you experience a lot of PRs queuing and a lot of them having duplicates. The 'allDuplicates' cancel mode will cancel ALL duplicates running in your repository - no matter if they are from the same repo/branch as your workflow and no matter if they were queued before or after your workflow.
This means that whenever any of of your 'workflow runs' starts running it will clean up the whole queue and get rid of all the duplicates there.