My sourdough has weird stains.Updated a year ago

Have you noticed something on the surface or around the rim of the jar that you have never seen there before? If you haven't fed your sourdough for a while, these could be signs of spoilage.You can now check whether it is yeast or mould. Creamy yeast is harmless, but mould is unfortunately a reason to dispose of your starter.

If at first you only notice a very small spot in your starter and you are not sure whether it is mould or yeast, wait a few days until you can better identify what it is.