Thanks for submitting the request - in the last two years I haven't seen it... did you find a way to turn it off?
I find them annoying too - particularly on a short interval where it takes up the whole screen, so I can't see how to change it.
What I do is to not set an intensity target at all, but rather add a note in the workout about what my target intensity for that interval should be too.
This is also preventing me from using the Training Peaks workouts my coach has done for me. This is completely nuts... I was hoping someone would have found a solution by now or Garmin would have resolved the issue. For now, I just rely on the Intervals function on my watch instead of the workout plans.