... According to halacha* eggs should not be removed from their shells and left in that state overnight. The halacha also applies to onions and garlic.
*Niddah 17a. [more-1, more-2].
The Unger's Mayonnaise label bears the text line "no overnight eggs" written in Yiddish and rendered in Hebrew letters.
Overnight eggs
Information logo on the label of a bottle of Elisha Mayonnaise, 950 grams, Belgium. Accompanying hechsher: Machsike Hadass, Antwerp, Belgium.