I didn't see any post addressing this specific issue:
In my Notebook, I have a number of Notes that contain binary info, sometimes it's images, and sometimes, it's files.
It appears that in some cases, the images are included directly in the body of the note (Base64?), and in other cases, they're listed as attachments, which shouldn't be an issue, if they're a copy within Joplin's domain.
However, yesterday, I had a note where I'd grabbed a picture (I copy & pasted the picture from the web), and then later, wanted to transfer it from the note where I'd grabbed it into a different note where I actually needed it.
I copied it from the "temporary" note and pasted it into the "permanent" note. I then deleted the temp note, and later, I noticed the image in the perm note was broken.
Attachment editing:
I have a Timeline file (the Timeline Project on SourceForge), which I keep in the notebook it is relevant to. I can Open... the file from the Note, and Joplin gives the banner saying it's only watching the file until I switch to another note. Unfortunately, as happens too often, I will accidentally switch to another note-- after all, it's where all my notes are! And then the connection is severed-- one time, I had to go find the temporary file and replace the one in Joplin to recover it.
What might be a better solution is to keep watching and keep the banner up there, even after switching to another note. Then have a button on the banner to tell it to manually stop watching.
This would both prevent accidentally severing the connection, and remind the user very clearly that they have something open.
(Odd bolds are for people who skim)