If you use /u/ instead of the dropdown box you get an instance agnostic link. eg /u/UnanimousStargazer@feddit.nl
You’re in lemmy.zip, so the link you see will be lemmy.zip/u/UnanimousStargazer@feddit.nl, which keeps you in your own instance so that you can message them, etc.
Just typing @UnanimousStargazer without selecting from the dropdown box does not create a link.