Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/LookupRef.php
public static function HYPERLINK($linkURL = '', $displayName = null, Cell $pCell = null)
    {
        $linkURL = ($linkURL === null) ? '' : Functions::flattenSingleValue($linkURL);
        $displayName = ($displayName === null) ? '' : Functions::flattenSingleValue($displayName);

        if ((!is_object($pCell)) || (trim($linkURL) == '')) {
            return Functions::REF();
        }

        if ((is_object($displayName)) || trim($displayName) == '') {
            $displayName = $linkURL;
        }

        $pCell->getHyperlink()->setUrl($linkURL);
        $pCell->getHyperlink()->setTooltip($displayName);

        return $displayName;
    }
public static function HYPERLINK($linkURL = '', $displayName = null, Cell $pCell = null)
    {
        $linkURL = ($linkURL === null) ? '' : Functions::flattenSingleValue($linkURL);
        $displayName = ($displayName === null) ? '' : Functions::flattenSingleValue($displayName);

        if ((!is_object($pCell)) || (trim($linkURL) == '')) {
            return Functions::REF();
        }

        if ((is_object($displayName)) || trim($displayName) == '') {
            $displayName = $linkURL;
        }

        $pCell->getHyperlink()->setUrl($linkURL);
        $pCell->getHyperlink()->setTooltip($displayName);

        return $displayName;
    }
HYPERLINK.

Excel Function:
=HYPERLINK(linkURL,displayName)

@category Logical Functions

@param string $linkURL Value to check, is also the value returned when no error
@param string $displayName Value to return when testValue is an error condition
@param Cell $pCell The cell to set the hyperlink in

@return mixed The value of $displayName (or $linkURL if $displayName was blank)