Pasted text from online contains grey, vertical rectangles - What are they, and how do you remove them?

I copied and pasted text from a website, and the text contains grey, vertical rectangles.

What are they, and how do you remove them? Can they be removed using regular expressions with the AltSearch (Alternative dialog find and replace)extension ?

Thanks for any information.

Maybe it is a Non-breaking space.
Try copy one and in Find & Replace, paste in Search and replace with nothing.

Better: replace with a space — see also → Highlighted black spaces?.

@manj_k one4you

If those are the non-breaking spaces, then the alternative solution is to disable the Field Shadings in “View” menu (or with Ctrl + F8).
This is better IMO because it’s done only once and preserves the non-breaking spaces which may actually be useful in the document.

If find&replace doesn’t work, I would paste it into NotePad to get rid of all formating. However, I am not sure if this helps you beyond the text example you show.