Concurrency Control and Degree of Parallelism
Limit number of concurrent runs of the flow, or leave it off to run as many as possible at the same time. Concurrency control changes the way new runs are queued.
Step 1: Open settings on the Flow trigger.
Step 2: When Concurrency control is turned off, Flow runs can continue to run in parallel without limitations or dependency on other Flow runs.
Step 3: When we turn on the Concurrency the Degree of Parallelism option is shown which specifies the number of parallel power automate flow runs that are allowed to Run at once and others will be waiting. In this case, only 1 Flow Run was allowed. Hence, the others were waiting.
Note: The Degree of Parallelism can be set to a certain number between 1 to 100.