Dear Maintainer,

Steps to reproduce in Debian Bullseye with Xfce 4.16 and gtk3-nocsd:
Install Firefox 90.0.2
Open any web page
Right-click on a link
Expected behavior: a context menu with choices such as open link in new tab,
open link in new window, bookmark link location, etc.
Actual behavior: the link is automatically opened in a new browser window.

Steps to correct the issue:
apt purge gtk3-nocsd
Reboot
Firefox's right-click on links behavior is as expected.