When an items model is dynamically changed via the item model definition, the particles do not respect this change and use the default model state for the particle texture.

(assets/minecraft/items/cooked_beef.json)
{
  "model": {
    "type": "minecraft:condition",
    "property": "minecraft:using_item",
    "on_false": {
      "type": "minecraft:model",
      "model": "minecraft:item/cooked_beef"
    },    "on_true": {
      "type": "minecraft:model",
      "model": "minecraft:item/cooked_beef_eat"
    }
  }
}

In this case, the model for cooked_beef is swapped to one with a red particle texture (minecraft:item/cooked_beef_eat) when using the item. This shows correctly in the gui and hand, but the eating particles instead use the minecraft:item/cooked_beef model instead of the _eat one as I would expect.

I've attached an example resourcepack that replicates this issue. With the resourcepack active, do the following:

• Give yourself a cooked_beef and start eating it.
• Notice how the particles use the normal beef texture instead of the red one from the minecraft:item/cooked_beef_eat model.