Set the browser.ml.chat.enabled and browser.ml.enabled to false as they intensively use the processor and drain the battery. All that to just find the best name for your tab groups. I prefer to have my laptop last one more hour instead.
replies(3):
Some quick digging in the source suggests that it's simply not enabled by default in ESR 128. I don't know if that's because it's only enabled by default in a later release, or because it's disabled in all ESR releases; I suspect the former. Compare [1] and [2]:
-pref("browser.ml.enable", false); # in upstream/128.14.0esr
+pref("browser.ml.enable", true); # in upstream/142.0.1
The other pref, browser.ml.chat.enable[d] is not mentioned in that file at all.(edit: according to [3a] and [3b], it's browser.ml.enable and browser.ml.chat.enabled... yay for consistency, I guess)
[0] https://sources.debian.org/src/firefox-esr/128.14.0esr-1~deb...
[1] https://salsa.debian.org/mozilla-team/firefox/-/blame/upstre...
[2] https://salsa.debian.org/mozilla-team/firefox/-/blame/upstre...
[3a] https://salsa.debian.org/mozilla-team/firefox/-/blame/esr128...
[3b] https://salsa.debian.org/mozilla-team/firefox/-/blame/esr128...