TLDR: this post is entirely to calm advertisers, it can be boiled down to "don't worry, we still prioritize brand safety like before". It does have this gem in it: "What has changed, however, is our approach to experimentation. As you’ve seen over the past several weeks, Twitter is embracing public testing. We believe that this open and transparent approach to innovation is healthy, as it enables us to move faster an…
Twitter was previously doing A/B tests. Spaces, communities, downvotes, circles, and even moderation were applied only to a subset of accounts while they actively experimented. The new policy is an objectively less scientific approach to testing functionality than what was occurring before.