I think the developers have copied the tab functionality from VS Code, a popular code editor. When you click a note, it will open the tab, but the text within the tab is in italics. This means you are just previewing the note. Clicking on other notes will replace the note that is being previewed. If you edit the opened note, or double click when opening the note, the tab will open in edit mode (the text will not be italicized). This tab will persist until it is closed.

Does that answer your question?

I too would like to see some settings for further customizing the behavior of tabs.

Yes, thanks, that is helpful. I have not seen that UX implementation before for tabs. It seemed to me, all the notes are visible in the panel to the left of the writing/editing pane. But, I only have 6-7 notes going, so I can see them all. If you had 50 or 100 notes, tabs would be better than scrolling down to find the ones you need to work on. So, tabs on Notesnook is a helpful feature for choosing and working on several notes out of many.

In the context menu it would be nice to have "open in new tab." Right click note in list, choose "open in tab" or "open in new tab."

This will be fixed in #6534