Instead of Draw.io or Figma (or Mermaid or any other option), I sketch around with Excalidraw and create diagrams with Miro. Miro took the world by the storm when corona hit and I am not super fond of the way people use it for everything from Kanban walls to whatever, but it does the diagram parts really well and works fast.

I bet I have wasted hundreds of hours fighting to get lines straight or arrows pointing to the correct direction with Draw.io - Miro they always just work.