Recently the exercise load benefit on my Garmin Forerunner 265s has been wrong. I had workouts where both my average heart rate and the average time in heart rate zone were clearly in my orange zone (threshold), yet the benefit is set as "base". Which is annoying, because my watch keeps telling me to have more high aerobic workouts and intense days.
In the screenshots, you can see the zones of today's workout, and the exercise load of today, which is "base" instead of threshold. Same thing happened yesterday.