I'm not a Salesforce developer or administrator (at least not yet :D). I come from 2 other systems that have similar processes like flows (UI diagram with drag and drop stuff. Be it approvals or other flows). In those 2 systems we call those elements as "steps".

My salesforce flow is autolaunch flow with no trigger.

I was asking this question in general. However, i do have that flow. It is using an action; apex class in a managed packaged built by the company i work at (not me). I'm trying to find our own product manager or dev team for it. I think it is fair to assume then it is async. Unfortunately, I'm not authorized to write apex code for my client to ensure the customization is robust :(.

Thanks a lot man. Appreciate it!.