@Diy - If the stray/orphaned text is in fact a mind map node object, what may have happened was an inadvertent duplication of a node using Ctrl+D (or Alt+drag). I had never thought to try this, but it actually works:

I am able to Ctrl + click and drag the stray text back onto the a node:
 

Is your text for sure a mind map node? Can you even select it by clicking on it? if it is a mind map node, it will have the plus (“+”) symbols on both sides:
 

If after

• signing out of Miro
• clearing the browser cache
• closing the browser and signing back in

you still can’t delete the object, I would suggest that you open a Miro Support & Help Center ticket.

@Diy - It looks like this may have been a bug and Miro has correct it. Now when I cut/copy-and-paste any Mind Map node, the new object becomes a new root/central node which can also be reconnected as a child or parent node onto any Mind Map.

In this example, I use Alt+drag to create a new Mind Map from a child node. I can then drag that new root node back onto the original Mind Map - another change that as made is that the Ctrl key is no longer required: