  The subreddit r/The_Donald was repeatedly denounced as a toxic and
misbehaving online community, reasons for which it faced a sequence of
increasingly constraining moderation interventions by Reddit administrators. It
was quarantined in June 2019, restricted in February 2020, and finally banned
in June 2020, but despite precursory work on the matter, the effects of this
sequence of interventions are still unclear. In this work, we follow a
multidimensional causal inference approach to study data containing more than
15M posts made in a time frame of 2 years, to examine the effects of such
interventions inside and outside of the subreddit. We find that the
interventions greatly reduced the activity of problematic users. However, the
interventions also caused an increase in toxicity and led users to share more
polarized and less factual news. In addition, the restriction had stronger
effects than the quarantine, and core users of r/The_Donald suffered stronger
effects than the rest of users. Overall, our results provide evidence that the
interventions had mixed effects and paint a nuanced picture of the consequences
of community-level moderation strategies. We conclude by reflecting on the
challenges of policing online platforms and on the implications for the design
and deployment of moderation interventions.
