You may configure some settings in <pack>/assets/minecraft/shaders/include/config.glsl


ROTATE_SPEED <Speed of rotation>

You may set place, where items will rotate by commenting strings with "//":
ADVANCEMENT_POPOUT: Advancement's pop-out icons
ADVANCEMENT_ICON_SELECTED: Selected advancement's icons. (Disabled by default);
ON_CURSOR: Items Dragged by cursor;
INVENTORY: Items in Inventory (thanks, cap);
ADVANCEMENT_ICON: Avancement's icons; Doesn't rotate in singleplayer, but rotates, when advancements are closed. (Disabled by default);
HOTBAR: Items in hotbar;

You may choose, what type of item will rotate:
FLAT: Flat items;
MODEL: Blocks and non-standard items (custom items);