Excerpt:
Most major subreddits show a decrease of between 50 and 90 percent in average daily posts and comments, when compared to a year ago. This suggests the problem is way fewer users, not the same number of users browsing less. The huge and universal dropoff also suggests that people left, either because of the changes or the protests, and they aren’t coming back.
Another factor that they probably didn't consider is that those 10% were, on average, more informed about what was happening and what happened in the past (see spoiler for examples). So for a lot of those people in the 10%, even if they didn't use the 3PAs (I predict that a lot of them were desktop users), it was the straw breaking the camel's back - I bet that some people felt outright disgusted for contributing with the profits of a disgusting company like Reddit Inc.
List of examples: