Debian has used the web browser Iceweasel rather than Mozilla Firefox since 2006 because of licensing issues with the Mozilla Corporation. Debian was initially permitted to use the “Mozilla Firefox” name for its browser but could not use the logo as it contravened Debian’s free software guidelines. In 2006, permission to use the Mozilla name was revoked. Debian decided to rebrand and since then Valve’s SteamOS (based on Debian) includes Iceweasel rather than Mozilla Firefox. However, in a bug report a week ago, Debian’s bug tracker pointed out that the two sides have agreed to cooperate and as a result the next release of Debian will use the name “Mozilla Firefox” for its browser, along with the logo.
https://www.pcworld.com/article/419749/iceweasel-will-be-renamed-firefox-as-relations-between-debian-and-mozilla-thaw.html