Had no bad batches at home scale, but quite often get these events, when even replacing the lock with an open fermenter does not help. Only regular cleanups work.
This is extra notorious escapee, witbier (OG 1065) made to dump frozen berries that remain in my freezer. And my very vigorous yeast.
The light finds its way. Modern lighting (especially bright stuff I use for lab lighting) is less harmful than sunlight, but still harmful and broad spectrum. Compared to foil consumption on tools sterilization, this foil is nothing.