Symbol navigator is polluted with thousands of system classes!

I have a test app. I added some extension classes to one of source code like below:

extension String {
    func addPathComponent(_ path: String) -> String {
        return (self as NSString).appendingPathComponent(path)
    }

    func sameText(with: String) -> Bool {
        return self.caseInsensitiveCompare(with) == .orderedSame
    }

    var isBlank: Bool { allSatisfy { $0.isWhitespace } }
}

extension Optional where Wrapped == String {
    var isBlank: Bool { self?.isBlank ?? true }
}

Now the symbol navigator is polluted with many system classes:

BTW, I am using Xcode 14.3.1.