How do I turn off "Quick diagram creation"

@A J Replogle - I don’t see an option to disable the new Smart Diagramming feature.

If you are ending up with unwanted boxes because you are trying to create connection lines vs. new objects, I did find that even though the connection line “blue dot” does turn into a smart diagram “blue triangle”, clicking-and-dragging the blue triangle does still create a connection line:

I would suggest that you also provide your feedback from within the new Smart Diagramming panel:

@Vlada - This may be worth noting in the Help Center 

https://help.miro.com/hc/en-us/articles/4403634496402-Miro-for-mapping-diagramming

Nice! Thank you. I was looking for a feedback area and didn’t realize how to get to it. I’ll add it there.

Also, I took your recommendation to hold the blue dot and that does let me then drag it to an existing object. So… pain point resolved. I was just in such a habit of click once to start a line and second click ends/connects the line that I didn’t think about holding the blue dot.