help for quality standard check on my submission

I’ve made a WP plugin which add a link preview on hover on the links of your site. It works also on mobile with tap.


It has been rejected for quality standard.
I’d like to understand if this “quality problem” is related to style or to code or to functionalities.

Here is the plugin in action:

The back office setting panel, which include also a stats panel for link clicks, is like this:

Can you help me to understand how to improve quality?
Thank you