The differing properties of vegetable-tanned hide over chromium-tanned is an interesting subject to read up on but I think it should be stressed here that a preference for one over the other for strops can be considered irrelevant, for multiple reasons.
Traditionalists often consider this a heresy and heated debates arise over it (particularly on straight-razor and knife forums it seems) with die-hard users insisting that veg-tanned horse butt is and always has been the best strop material going and anybody who says otherwise is not to be listened to, or something along those lines :-)
This is one of many points of contention that contribute to the high noise:signal ratio surrounding sharpening.
Because of this it's very easy to get bogged down in esoteric points like do I have to have veg-tanned leather? Should it be horse butt, or is bull neck leather better like someone else said? Or should I listen to those guys now promoting buffalo hide as THE strop material, better than anything that came before?
All of that is irrelevant if you just focus on results. Does your strop do what you want: remove a microscopic burr (also called a wire edge) and/or polish your edge? And does it do it efficiently?* If so that's all that matters.
And here is where stropping compound becomes obvious as the key factor. It is the stropping compound that does almost all of the work.
So not only does the type of leather not need to matter, you don't need leather at all. A few woodworkers today use strops just made from MDF or harder woods like maple with the stropping compound loaded onto the surface, and in head-to-head tests of denim-faced strops with leather-faced strops denim seems to do the job just as well. And for most of us denim scraps of large size can be had for free, which can't be said for vegetable-tanned leather.
*By efficiently I mean in perhaps 30 seconds, not the many minutes some people spend stropping razors on bare leather strops. We don't have time for that, we have wood to get back to.