@orakel,
Currently, if the pasted image has an absolute URL like this one:
https://example.com/images/mypic.jpg
it'll be automatically converted to an image when a comment is displayed if the option called "Image Source URL to Image Conversion" is enabled. The option is located in the Dashboard > wpDiscuz > Settings > Comment Content and Media admin page. In short, using this option you can enable/disable image URL to image HTML conversion.
If the pasted image has the following code:
<img src="data:image/png;base64, iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
9TXL0Y4OHwAAAABJRU5ErkJggg==" alt="Red dot" />
it'll be automatically removed. In other words, there is no way to upload an image directly by pasting it in the comment content.