Chromium 103.0.5060.53 on FreeBSD 13.1-RELEASE
KeePassXC-Browser Version: 1.8.3.1
KeePassXC 2.7.1

Impossible to connect to database.

Following the troubleshooting guide, I found that org.keepassxc.keepassxc_browser.json is not installed in ~/.config/chromium/NativeMessagingHosts, but in ~/chromium/NativeMessagingHosts.

Symlinking the two folders has solved the issue.