In addition to the clipboard hijacker malware, there is another common possibility. It is possible that you failed to copy the address when you attempted to. In that case, whatever was the last thing you copied would still be on the clipboard. So, if you had recently copied a bitcoin address from somewhere for some other purpose, your paste would have pasted that older address from your clipboard instead of the new one that you were attempting to use.
I though about that as well. That's why I asked him this:
is it possible that you did some other work with bitcoin and addresses while copy/pasting that address from your friend, which could have resulted in you accidently copy-pasting a wrong address instead of the one from your friend?
Op never mentioned if he was using the mobile or desktop version of Electrum. One thing I have noticed with my mobile phone (it's not related to bitcoin or Electrum though), is that sometimes when I copy a link to send to a friend, my phone sends the wrong link of something I visited and copied before that last link I sent. If that can happen with normal link to videos or articles, I would think it can happen to addresses as well. I sometimes see that with Facebook or Instagram videos. I copy a specific link, send it to a friend, and he receives the link to the profile page of the poster and content creator instead. I hope you understand what I am trying to say.