Using the specified power on something like minecraft:respiration will not do anything unless the power holder has a helmet on. Same thing goes for minecraft:fire_aspect, if the power holder doesn't have an item in their main hand, it doesn't apply the enchantment anymore.

Example code:

{
    "type": "apugli:modify_enchantment_level",
    "enchantment": "minecraft:fire_aspect",
    "modifiers": [
        {
            "operation": "add_base_early",
            "value": 3
        }
    ]
}

Tested on Apugli 2.4.3 on Minecraft 1.20.1

Strange, because I thought that I made a check for this.

I'll look into it now.