Cats effect 2 nested evalOn/blockOn gotcha

blockOn.scala

import cats.implicits._
import cats.effect.{Blocker, IO, IOApp, ExitCode}
import java.util.concurrent.Executors

object Test extends IOApp {
  override def run(args: List[String]): IO[ExitCode] = {
    val blocker = Blocker.liftExecutorService(Executors.newCachedThreadPool())
    blocker.blockOn(
      for {
        _ <- printThread
        _ <- blocker.blockOn(printThread) >>
        printThread //DANGER! This runs back on the main compute pool
                    //as the pool to shift back to is determined by
                    //the ContextShift in scope, rather than where
                    //it was executing before
      } yield ()
    ).as(ExitCode.Success)
  }
  def printThread: IO[Unit] = IO(println(Thread.currentThread().getName()))
} 

//[info] compiling 1 Scala source to /Users/tim/dev/test/target/scala-2.13/classes ...
//[info] running Test
//pool-31-thread-1
//pool-31-thread-2
//ioapp-compute-1