Absolute path for nggallery.css

I have just noticed (by chance) that NextGEN-gallery outputs a link to the file nggallery.css with an absolute path (instead of the plugin-path). I did not notice this before (so I cannot say, when the absolute path has been added). The site where I found this link has not been moved, nor has there been any major change in the last 14 months.

<link
rel='stylesheet' id='NextGEN-css'  href='http://domain.tld/here/.is/the/absolute/path/wp-content/plugins/nextcellent-gallery-nextgen-legacy/css/nggallery.css?ver=1.0.0' type='text/css' media='screen' />

Could you tell me on how to fix this absolute path exposing link?

https://wordpress.org/plugins/nextgen-gallery/