Huge disscrepancy between pace and hr zones at aerobic range

So I have recently (6 weeks ago) returned to regular running (or any regular exercise really) after a long break. I’m a male nearing 50.

I’ve been training with Athletica for two weeks now in the train to maintain mode, just having finished my test week. I have some weeks of base training ahead of me, but this is to be expected given where I am.

I seem to have a huge discrepancy between the Z2 pace and hr: Athletica has fixed my top of Z2 at 125 bpm, which for me seems to be a pace of 11:30/km (!). The Z2 pace according to the model is supposed to be at 7:48.

on the other hand if I were to run at at 130 bpm I seem to get a pace of around 7:50-8:10. I don’t really understand physiology enough to judge why there is a such a big difference.

so currently I can either “run” my easy runs at 11:00 pace, keeping in the HR zone as suggested by Athletica, or run at the pace suggested by the model, but with a higher heart rate. I can easily go on for 1h+ at this 130 bpm heart rate, and this is what I think is the conversational pace. The AI coach then shouts at me for being in Z3 and shortens the following workouts.

What is likely to be more beneficial over the next couple of months of base building? I would prefer to run at the faster pace, but there apparently is some magic that happens at low hr I wouldn’t want to miss out on…