Firefox died long ago.

It was an engine fight, and Mozilla decided not to participate.

This is why I’ve stuck with firefox through thick and thin

Brave, Vivaldi, Edge and other chromium browsers are forks of the main chromium project. They can decide whether to include or exclude features from mainstream chromium.

As far as I know, Brave and Vivaldi will keep Manifest V2 extension support and said that they will not ship WEI (Web Environment Integrity).

Discord uses a modified version of electron, and it’s also probably an outdated fork as well, although I am not sure about that.

Steam, in the other hand, uses CEF, which they use as a way to render it’s interface and as a replacement of VGUI (a good example of this is the steam game overlay), I don’t know if they will ship WEI if it ever releases in chromium as there isn’t a statement from Valve yet.

Sources:

• ARSTechnica, Chrome’s “Manifest V3” plan to limit ad-blocking extensions is delayed, https://arstechnica.com/gadgets/2022/12/chrome-delays-plan-to-limit-ad-blockers-new-timeline-coming-in-march/
• GHacks, Brave confirms it will support Manifest V2 extensions like uBlock Origin even after Chrome drops them, https://www.ghacks.net/2022/09/29/brave-browser-manifest-v2-extensions-after-v3-update/
• Valve Developer Community Wiki, Chromium Embedded Framework, https://developer.valvesoftware.com/wiki/Chromium_Embedded_Framework
• Github, Discord’s Electron Fork, https://github.com/discord/electron

If I missed something, please tell me!

Firefox with add-ons. Especially, but not only, Ublock Origin.

Um actually… Opera and Edge weren’t always based on chromium!