It's going to be hard to tell definitively, because so much traffic on the major platforms like Reddit are bots. As a percentage of overall traffic, the reduction may only be a few percentage points.
But all that traffic that is leaving are from Actual Humans. Humans who cared enough about their interactions to have preferences about how they engaged with Reddit. In a few years, Reddit will just be a bunch of bots talking to each other.
One of the founders of Reddit mentioned in an interview a while back that it was all bots when it started, to give the illusion of being populated when it was too new to have any users except the people who worked on it. From bots it came, and to bots it will return. The circle of life.