by default, suspending a user or instance does not prevent that user or users from seeing posts on my instance. this should be clarified in the Moderation actions documentation under the Individual Moderation and Server-wide moderation sections. this default behavior is surprising for many admins and may be a safety concern in the case of harassment - see this issue thread.
the documentation should further clarify that it is possible to prevent suspended users from seeing posts, by enabling the AUTHORIZED_FETCH environment variable. currently, the existence of this feature is not mentioned in the Moderation actions documentation.