❔ Regex help

I have this regex:

(?<![\[\]])(?:"&QUOTE&"([^"]*?)"&QUOTE&"|[^",\[\]]+)(?![\[\]])

(?<![\[\]])(?:"&QUOTE&"([^"]*?)"&QUOTE&"|[^",\[\]]+)(?![\[\]])

And when pasting to C# it looks like this:

var regexMatch = Regex.Match(fileText, @"(?<![\[\]])(?:""&QUOTE&""([^""]*?)""&QUOTE&""|[^"",\[\]]+)(?![\[\]])");

var regexMatch = Regex.Match(fileText, @"(?<![\[\]])(?:""&QUOTE&""([^""]*?)""&QUOTE&""|[^"",\[\]]+)(?![\[\]])");

In regex101 it works properly, but when pasting to C# it only gives me a single match. Why?