Leaf miners, unless you get a serious infestation, are one of the most benign of garden pests. The amount of leaf tissue they consume doesn't matter to the plant.
Their life cycle is that the larva tunnels around inside the leaf (where it is not vulnerable to any sprays) eating leaf tissue from the inside. When it is ready it chews its way out of the leaf and drops down to the ground below. It burrows shallowly into the soil where it pupates. After a week or two, the adult emerges. So you can help prevent the next generation by having a weed barrier in place under affected plants, so the larva can't get to the soil.
Lambsquarters and velvetleaf are trap crops for them. If you have these growing near the things you want to protect, the leaf miners will attack them preferentially. Those big soft leaves of velvetleaf are a magnet for them:
I used to have some of this growing in my garden and almost never had leaf miners on anything else. You just have to keep pulling infected leaves off the velvet leaf.
Velvetleaf is non-native, but it is useful to pollinators and beneficial insects:
" The nectar and pollen of the flowers attract various kinds of bees, including bumblebees, long-horned bees (Melissodes spp.), leaf-cutting bees (Megachile spp.), and Halictid bees. Occasionally, small- to medium-sized butterflies visit the flowers for nectar, while Syrphid flies feed on the pollen (Robertson, 1929)." https://www.illinoiswildflowers.info/wee ... etleaf.htm