It depends on the texture and density of the fermenting food/substrate. In some cases such as hard cheeses the mycelium doesn't penetrate very deep which means

It depends on the texture and density of the fermenting food/substrate. In some cases such as hard cheeses the mycelium doesn't penetrate very deep which means the mold part can be cut off and the rest is still reasonably safe to eat for anyone who isn't immuno-compromised. Although generally if there's unintended mold on home made fermented foods it means something went wrong in one of the preparation steps e.g. acidity too low, moisture too high, something was exposed to air instead of submersed in brine. Many Chinese language Youtube tutorials on fermented chili sauce also suggest thoroughly wiping the inside of the container with high ABV spirits before adding the mixture.