Well, no one wins since they no longer use beef tallow, but do add beef flavoring to the spuds.

So we can't eat them and people who liked the tallow-fried ones don't enjoy them as much (?)

The “natural beef flavor” doesn't, AFAIK, have beef in it (except insofar as hydrolyzed milk protein, originating as it does in a cow, is “beef”.) The construction “natural X flavor” in an ingredient list means “flavorings that can legally be described as natural which are intended to simulate X”.

So is this to say that McDonalds' fries are lacto-ovo-vegetarian, but not vegan? I'm not vegan myself, but I find this a strange category for fried potatoes to end up in.

McD's fries died the day they stopped using tallow.

I'm still saddened that Pringles aren't cooked in peanut oil any longer - they tasted so much better before; now they're fairly bland (regular version).