For some reason, in the bottom right corner of my webpages I am seeing a pop-up window:

Notice:
 com_content.category: Field=null
com_content.categories: Field=null
text: Field=text
mod_custom.content: Field=text

the content in the pop-up differs depending upon the page I am looking at but generally, I always see:

text: Field=text
mod_custom.content: Field=text

is this something which related to framework?

have either the URL in the in content.