It is difficult to predict how people react with limited information. I think hypothesis for this change was "well being might improve but we're not sure" and at the same time "engagement might drop because there might be folks out there who enjoy collecting likes and this makes it less fun but we're not sure". And it's hard to tell what the results will look like based purely on speculation.

I don't know what makes you certain you know the answers even though you've looked at none of the data. Do you have some other sources?