Why does [NaN].includes(NaN) return true in JavaScript?

According to MDN’s document say that

Note: Technically speaking, includes() uses the sameValueZero
algorithm to determine whether the given element is found.

const x = NaN, y = NaN;
console.log(x == y); // false                -> using ‘loose’ equality
console.log(x === y); // false               -> using ‘strict’ equality
console.log([x].indexOf(y)); // -1 (false)   -> using ‘strict’ equality
console.log(Object.is(x, y)); // true        -> using ‘Same-value’ equality
console.log([x].includes(y)); // true        -> using ‘Same-value-zero’ equality

More detailed explanation:

1. Same-value-zero equality similar to same-value equality, but +0 and −0 are considered equal.
2. Same-value equality is provided by the Object.is() method: The only difference between Object.is() and === is in their treatment of signed zeroes and NaNs.

Additional resources:

• Which equals operator (== vs ===) should be used in JavaScript comparisons?
• Array.prototype.includes vs. Array.prototype.indexOf
• Are +0 and -0 the same?