The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.
The remote host is running SeaMonkey web browser.
The remote host is running the SeaMonkey browser, which contains much of the same underlying code as Mozilla Firefox.