This isn’t a legal loophole, the disclaimer is just unregulated and might not hold up in court. All ingredients have to be listed under ingredients, if they’re contained:
https://www.lebensmittelklarheit.de/fragen-antworten/unterschied-kann-spuren-von-und-kann-xy-enthalten
That being said, I, too, started avoiding Burger King, when their allergy information sheet contained all three versions of this disclaimer. (“May contain”, “May contain traces of” and “May be cross contained with”)





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They didn’t thank Scribble (the dog) in their acknowledgements section. 1/10 paper, would only look at the contained dog picture