Skype opening links in wrong browser
I uninstalled the version that came from the "Ubuntu Software" app and downloaded the .deb directly from skype.com. Although it's the same version number, this does not have the link problem.
It's due to Skype being installed as a Snap package, I assume with wrong configs at the snap sandbox level.
The easiest solution is just to install the .deb installer file from Skype directly.