Heart Rate Zone for Strength Training

As you observed by yourself already, when doing strength training the heart rate is a bad indicator for the actual training load. So ignore the metrics given by Garmin in regards to aerobic and anaerobic training effect. They only make sense when you do workouts such as running or cycling. I'm not even sure why my watch always tells me this after doing a strength training. They are completely useless, and say nothing about the training effect or load.
I'm surprised by this, because Garmin actually HAS other metrics available which they could take into account when computing the training effect of weight lifting sessions, e.g., for every exercise I do, I provide the weight I lifted. So based on my body weight, the history of my training and the total amount of weight I lifted during the given session, they could compute a more precise "training effect", then just taking my heart rate....

Edit: Ok, maybe the reason is, that the watch is not very good in detecting which exercise I do. So if I weight 80kg and do bench press with 100kg, it's probably less effort than doing, e.g., biceps-curls with 100kg. Or maybe not. But anyway you understand what I'm trying to say, if the watch can't detect the exercise it doesn't know how much effort it is.
Garmin should just completely scrap the information about the training effect when doing workouts other than running, swimming and cycling. It seems they put the additional workout settings half-baked into the app, without thinking about other "side effects".