There is sometimes the idea that xylitol is dangerous. This is related to the intake of the product. You should not consume more than 35 grams per day because it can cause digestive issues. The amount in the B12 lozenge is so low that it has little impact.
The reason Vitakruid includes xylitol in very small amounts in the B12 lozenge is because B vitamins often have a very unpleasant taste, which can decrease adherence to the therapy of taking this supplement.