Not sure about the serial numbers, but a community member sent one in from 2018 and it very obviously has the older pads on it, and they measure differently.
Old unit:
Unit from 2021 (they most likely made the change to the pads sometime in 2019):
And side by side. You can even see that on the newer one (right) the front part is thinner as well.
So, yeah it’s not a myth. Let the issue be put to rest.