I find it's usually slugs and snails.
Some dry mulch around the plants, like straw works well if you haven't done so already.
Discussion
I can confirm go out and pick at like 6:30am when there is dew on the ground still and a chill in the air. Pick the strawberries and you will find slugs on a few. Can’t be 100% certain this is your picture though.
My 85-year-old mother said the exact same thing. She also asked if we recently had a big rain. Apparently slugs are a lot worse the day after a rain.