When I need to copy the link of the thumbnail, I would right click to tab the page of the browser in order to access the address bar.

How were you doing before? Did you do a simply click and after copy the address go back to the page?
Otherwise you can still right click on the thumbnail and chose "copy link" (or "copy target" or something like that, depending on the browsers), as before. Even with the added javascript popup the link at HTML level as not changed.
Or just right click on the enlarged image displayed in the popup and chose "copy image link".
I could easily add a "copy link" button in the popup, if it is handy.

By the way, earlier today I fixed a small bug: the edited comments were always included in the "Last edit: ..." mention the username, but the username is supposed to appear there only when edited by someone else (an admin).

Right, I didn't think about the 'copy image link' when clicking on the image, I just used to copy the link at the top of the page.
Solved

I've noticed a strange bug on mobile. For some reason, i can no longer click on anything on the right half of the page unless i flip my phone sideways. This only happens on this website specifically.

Do you mean that it happens when you are in vertical mode or in horizontal mode?
Which web browser do you use?

It happens with both but it's far more noticeable in vertical mode.

I use Firefox.

I test mostly with Firefox and I didn't had that problem. Maybe it is due to some ads? You could try blocking them just to check if it is caused by that (as they depend on the country, maybe you get some that cause issues)

Small update for the popup of comment images: if a timetag can be guessed from the picture name, it is displayed. There may be cases where it is wrong in some cases, or not detected where it should, I can try to tweak the code if needed.

You can check in the thumbnails I post, e.g. in https://www.imcdb.org/yourcomments.php?formovie=33550045