I’ve spent a lot of time trying to evangelize Lemmy on reddit, and one of the most common criticisms is the possibility of defederation and getting cut off from major communities.

Frankly, if this is a concern to people and I believe it does concern some, they should not use federated platforms as this will always happen.

We know that Lemmy slowly bled tens of thousands of users in the months following the reddit API exodus as users drifted back to reddit. Although it’s impossible to know how many of those users were annoyed by the defederation drama, I think it’s safe to say that the number wasn’t zero.

The steep decline in active users on Beehaw in the months following the decision is probably the best source of hard evidence supporting my claim.

You're saying that the decline in active users on Beehaw is a result of these defederations while simultaneously acknowledging that Lemmy as a whole lost users. Maybe it is true, maybe it is not. I could not make such a claim with this information.