for the record, firefox for android also integrates the google backdoor for the sole purpose of allowing chromecast for videos... which zero users use or want.
well FTR, IceCatMobile (downloadable via F-Droid) I doubt would have that backdoor.
check the last build date.
it's so hard to remove the gapp dependence used for that tiny feature that the icecat maintainers just gave up.