Sigh, let me copy and past from my other correction post I attached elsewhere on the chain...
Let me correct some misinformation. browser.ml.chat.enable is to enable or disable the sidebar connection to LLM chatbots. That feature just gives you a chat interface to an LLM of your choosing on the side without opening it in a web page. It has nothing to do with local inference or with naming tab groups. And only requires as much energy as any other page, as LLM chatbot pages don't do local infernence. Anyway this would only be active if you have that part of the sidebar open, and have clicked to agree, and selected an LLM from the list. But if you turn off browser.ml.chat.enable then you won't see it all.
Firefox also has a couple ML local features that don't involve connecting remote ML system, which means that when they are used you are doing local inference, which could be a power draw. On the other hand it means all data processed or produced is private and no third parties see it. These include:
Generating missing alt text for images, for now limited to PDFs being displayed in browser
A built in web page translation option, currently only a few languages
Enhanced tab groups, which can auto name a tab group, and can offer to put more related open tabs into the the group
Enhanced link previews, summarizing pages on the other end of links when you hover over them (I think this is only turned on in developer/nightly builds still for now?)
The first two are not terrible ideas IMO. The second two are pretty silly I think.
These local ML options can be fully turned off with browser.ml.enable (that might also turn off the chat option above, but not positive) Or they can be turned off with individual options:
browser.translations.enable
browser.tabs.groups.smart.enabled
browser.ml.linkPreview.enabled
It is worth noting that I believe all of these except maybe the alt text (not sure about it) ask if you want to use them. Of course if something weird pops up a lot of users just try to get rid of it and might end up agreeing. You can see this opt-in requirement with the existence of preferences like browser.ml.linkPreview.optin which record if the user has opted in. You can change that if you like, but note that setting the "enabled" version of that pref to "false" will disable the feature even if "optin" is set to true.