I did a number of tests, and there are structural differences between the topology results of ZRemesher V2 and V3, also on organic models (sometimes only minor differences though). It’s probably the new way of scanning for hard edges that affect the results, or an altered algorithm altogether.
The alternative Alt + ZRemesher algorithms also differ from each other when the Legacy button is activated or deactivated. So you’ve got four chances of achieving the topology you’re looking for since the release of ZBrush 2019.
I wonder if Maxime has used the same algorithm for ZRemesher 3.0 as he used for QuadRemesher. It seems a bit unlikely that he developed it as an improved feature for Pixologic, and would then be free to sell it himself as a plug-in for other 3D editors. Unless Maxime is a tough businessman who has chained Pixologic to a smart licensing deal.
I would rather guess Maxime has left Pixologic after creating the previous ZRemesher years ago, and has now created a new algorithm to sell himself, while Pixologic’s developers coded their own changes to ZRemesher.
I could ask Maxime, but I don’t want to bother him too much.