Alright, I've probed every last depth of the internet to find the answer to this thing and the best evidence I've come up with is this.
What seems to be the case is that either Facebook has glitched itself out or they have issued a limited release of this function in certain countries (India) as some form of beta testing. Thus far no mainstream media or any other credible source apart from internet speculation as to this functions release.
However this topic seems to be picking up considerable interest, so one can assume a large number of people are affected, in which case Facebook should release a press statement either today or tomorrow or some other coverage should take place.
I will keep this answer update with any new information.
- Update 1 : May 11 2017 Update from TheDailyDot Indicates existence of
thankful emoji, but no mention to the year? and does not describe it
as a new feature. Perhaps it is recurring feature for every mothers day?
- Update 2 : May 12 2017 Update from the metro as far as it shows the thankful reaction is now being rolled out across the word to coincide with the American Mothers Day which falls on the 14th of May
. It can be used throughout this weekend as a normal reaction but will disappear afterwards. The Stack Exchange network simply noticed this phenomenon hours before any major newspaper or even an official press release. Good Job Guys!!
- Update 3: May 13th 2017, Update from TechCrunch Full complement of Mothers Day features released including cards, stickers, masks, filters etc.
IMPORTANT SIDE NOTE: I personally have not observed this phenomenon on my own Facebook, and only seen such reactions appearing on certain friends from certain countries. I therefore conclude this roll-out is limited to countries who celebrate mothers day on the 2nd Sunday of May.
Below is a list of countries that celebrate Mothers day on this day. If you do not reside in these countries you may not see this feature on your Facebook.
Antigua and Barbuda
Papua New Guinea
Saint Kitts and Nevis
Saint Vincent and the Grenadines
Trinidad and Tobago