package a {
  class DeveloperApi extends scala.annotation.StaticAnnotation

  /** Some doc here */
  @DeveloperApi
  class A

  @DeveloperApi
  class B
}

Class A gets a simple comment (Some doc here) but not the annotation. Class B gets the annotation.

Tracked the problem down to: https://github.com/scala/scala/blob/cac6383e6658dc5956540b76b9b46c3b664774ac/src/scaladoc/scala/tools/nsc/doc/html/page/Template.scala#L309-L311. It basically says: if the member gets its own page, and the doc comment is defined, don't generate anything but the doc comment. In our case, A has a doc comment and B doesn't, therefore A only gets the doc comment while B gets the full comment, including the annotation => inconsistency.