As more people continue to join in the national conversations, demonstrations, and protests surrounding racial justice, Instagram has taken note. The black heart icon is added to stories that use specific, racial-justice-themed Instagram stickers. That way, you can see at a glance who might be posting about the Black Lives Matter movement, antiracist books they’ve read, or petitions to sign, for instance.
This isn’t the first time Instagram has changed up the appearance of Instagram story icons. You may have also seen a bunch of rainbow story rings (rather than the orange / pink gradient ring that typically appears when someone has a new story). The rainbow rings are there to signify when someone uses one of Instagram’s Pride-themed hashtags or stickers in a story throughout the month of June. It’s a small detail, but some people were low-key obsessed with getting that rainbow.
Source : https://www.distractify.com/p/black-heart-on-instagram-story