Noto Color Emoji is partially used
Also happening in Gentoo. In summary, with Google Chrome and Firefox, sometimes some emojis are shown with Noto Color Emoji while others are shown with the old B&W style.
For example you can see many examples simply looking to the comments of many youtube videos as people seems to like to use a lot of emojis on them and you can see some use Noto Color Emoji while others not: https://www.youtube.com/watch?v=gAirINwjaxE https://www.youtube.com/watch?v=bDb5QMRTCPI https://www.youtube.com/watch?v=bbEoRnaOIbs (and many other random examples)
Looking to "Inspect element" Firefox tool, in "Fonts" section, I see that "Dejavu Sans" is being used to show emojis instead of Noto Color Emoji. I have seen that current default /etc/fonts/conf.avail/60-generic.conf only sets Noto Color Emoji for emoji while, probably, it should also be listed for other "families" to be used over ugly emoji fonts from other font sets