Are you a light person? Those 10x15x4 bearings have inherent limitations in maximum load. It's a simple question of geometry, smaller balls means smaller contact patches and there are only so many Newtons they can stand before being crushed. And if they are operated close to that limit, lifetime will drop. Pedal powermeters can't really do without low profile bearings on the inboard side, due to the hollow axle that needs a certain amount of volume for sensor installation.
Some well-respected pedals (non-PM) actually have friction bearings on the inboard side, placing a particularly strong outboard bearing so far inboard that they take the entire load at typical PCO. Perhaps that wouldn't be the worst approach to a hollow axle PM pedal, but then on the other hand standard ball bearing availability is so much better than replacement friction bearing availability and lifetime expectations of PM pedals and non-PM are surely not the same.
But it's actually possible that they did a change in 2017: they could have switched from regular bearings (fewer balls, but separated from each other's) to cageless. Cageless have more balls, therefore considerably higher load capability, but more wear from spinning. But from the ball bearing point of view, even a cadence of 160 is barely moving at all (they are designed for four to five digit rpm...), so I'd expect cageless to last longer. But I doubt that they changed, I'd be really surprised if they ever touched their bearing supply because of wear, not without also switching to 6700-RS (rubber sealed).
But cageless 6700 (often called "max" for "maximum complement") are incredibly hard to find, I was once able to order some, but given the total absence of that configuration for 10x15x4 in Google hits I now wonder if I actually just got regular 67002RS that somehow got mislabeled.
