Steps to reproduce

1. Create two folders a and b
2. Select both folders
3. Start dragging the two folders by clicking on folder a or b.

Expected behaviour

It should not be possible to drop the two folders onto themself.

Actual behaviour

It is possible to drop the two folders onto the folder which was not clicked for starting the drag, see the image:

Of course, moving folder b into itself fails and produces an error message:

But since I wanted to move both folders, moving folder a into folder b is not the intended result.

Server configuration

Nextcloud version: stable18 as of 8b4b3e1