Hey @lion
Same thing was happening for me as well. My flow ran fine 5 times and when it went to 6th run it started throttling. So, in your case as well its throttling.
There is one bad thing about power automate, till the apply to each step does not finish we cannot even see inside whats happening.
There would be a step/action in your flow which is throttling your entire flow.
Can you share your flow in edit mode, lets see what is the scope of improvement.
Final verdict can only be given when the flow run finishes. So let it run, I hope it finishes till tomorrow 😂.
And as soon as it finishes check yourself what is the problem and add screenshot here as well.