When trying to connect to the KeePassXC browser plugin to the database's browser integration, it should connect, however, it errors out with "Key Exchange failed." I believe the reason for this bug is Mozilla's request to move to Snap as the default starting with Ubuntu 21.10.

Debug info

KeePassXC - 2.6.6 Revision 9c108b9
KeePassXC-Browser - 1.7.9.1
Operating system: Ubuntu 21.10 amd64
Browser: Firefox 93.0