If the method is patented, you can only apply for invention, not utility model.
The main differences between product patents and method patents are as follows:
1, with different protection objects:
Product patents protect the shape and structure of a product; Methods Patents protect the process and flow of manufacturing a certain product.
2. You can apply for different patents.
The technical scheme of product category can apply for invention or utility model;
Methods You can only apply for invention, not utility model.