In a lot of other programs, ctrl+shift+V pastes without formatting, but Joplin doesn't do this.
I keep ending up with formatted text pasted into the middle of my note, and in addition Joplin doesn't actually support what was pasted but it stays like that until I reload the note.
Joplin does the same but the current stable version v2.9.x has a bug which prevents Ctrl+Shift+V from working. At the moment, you need to update to the v2.10.x pre-release if you want the shortcut to function properly.