in single player, it generates new tiered items/itemstacks in the inventory as one picks up/puts down, hovers over items. the nbt is not actually changed, this appears to be a clientside issue (Though single player shares object memory so it becomes serverside in single player)

setting render_item_model to EQUIPMENT or ALL will cause the issue. setting it to NONE removes the issue leading me to believe its an issue with itemstack modification/recreation during rendering?

issue is with iceberg equipping items clientside during a render call. since equipping items normally happens serverside, the tiered code didnt check sidedness during tier generation