In the long-forgotten time of 2019, Instagram announced the start of a test to hide Like counts users usually see on everyone else's posts. Over the last year of the COVID pandemic that test has still been going on, but without much update or expansion. Then today, many Instagram users in the US got the above notification saying they wouldn't see Like counts anymore, but without any official announcement.
Instagram told Engadget that today's expansion was a bug, explaining in a tweet that "We unintentionally added more people to the test today." So if you got the message and change today, expect to see it roll back to normal soon.
We've been testing a new experience to hide likes on Feed posts. We unintentionally added more people to the test today, which was a bug — we’re fixing this issue and restoring like counts to those people as soon as possible.
— Instagram Comms (@InstagramComms) March 3, 2021