Do you happen to have the Note Link System plugin installed?
This sounds like one of its (cool) features since v0.7.0. It's supposed to display the icon of the URL, but maybe in your case this doesn't work and hence the square is shown instead.
If this is the case, go to the NLS plugin settings and look for this line:
Change it to "Don't fold url" to return to the regular Joplin behavior.
1 Like