# $item replace entity @s weapon.offhand with potion[item_model="$(texture)",potion_contents={custom_color:$(start)},attribute_modifiers={modifiers:[{id:"attack_speed",type:"attack_speed",amount:-1000,operation:"add_value"}]}] 1

# item modify entity @a weapon.offhand from block 33 -60 -11 my_pack:copy_potion

# loot replace block 33 -60 -11 container.0 loot main:copy_potion

$item modify entity @s armor.head {function:"set_components",components:{potion_contents:{custom_color:$(start)}}}