https://www.warzone.com/Forum/499444-alloyitem-recipes-change-level-level

If someone still wondered whether this can happen or not, I've just sold all my zinc because no recipe in the previous level made use of zinc. But one recipe that formerly used copper wire now uses zinc instead (don't want to spoil too much). So, although I was ready to accept that any new recipes may require stuff that previously was just for sale (and techs), in fact all recipes are potentially subject to change even within one version of the idle maps (both levels were/are v15 of the idle maps).

I get that the quantities of ores per alloy or alloys/items per item change slightly to compensate for oddities/imbalances in each map. But the complete change of recipes is crazy. Definitely an aspect that I don't really understand. I mean, ask any black smith, how many recipes for bronze there are (except for small quantity additives to achieve specific properties). I only know one.

Yes, they change.

some stay the same. screws always need iron, tin cans always need tin. But yes, many other items change from level to level. In higher levels, there is usually something that you can use it for (structs, bolts, and rivets take enormous amounts of lead, nickel, and zinc).