New install/New user 
After every code block I get the text "⧉ Copied!" on a line right below the block. I can't figure out where this is coming from and how to stop it. If I remove it, it just comes right back.
Anybody seen this behavior?
MacOS Ventura 13.3.1
Joplin 2.9.17 (prod, darwin)
Sync Version: 3
Profile Version: 41
Keychain Supported: Yes
Revision: a84a8e7
Your screenshot seems to show how it looks when it works. How does it look when it doesn't do what you expect?
Have you installed the code-clipboard plugin?
This adds the same icon and the tooltip says "Copy" or "Copied!" depending on whether you have clicked it or not.

I managed to duplicate what you are seeing.
It looks like the code-clipboard plugin does not work with the Rich-Text editor, only the Markdown editor.

If this plugin is useful to you it may be worth rasing an issue on the author's GitHub repo (linked in the post above).
Yeah. Pretty sure it was code-clipboard plugin. I removed it and looks like the problem went away. I was just looking for a little icon to click when I wanted to copy the code block to my clipboard.