It looks like slug damage to me. Modern slug pellets use iron salts to kill them, which are not that harmful to other things. Remember they are 'slug bait', don't put them too close to the plants, you don't want to attract slugs to them, but scatter in the vicinity, scatter a few at first, if they disappear leave a few more next day, and so on until there are some left. That means you use the minimum necessary.
With the iron the slugs go back to their 'home' to die, the old metaldehyde pellets used to make them produce huge amounts of slime and die on the spot, messy, but satisfying.
