What's the 'T' in auto completion as I type 't', and how to get rid of it?

[DragoonKiller]

This is a newly created untitled file, without any project opened. And here's a 'T' on the top of auto-completion.
Each time I want to type identifier 't' it comes out and take the first place... Which is really annoying..

Disabling C# extension will remove all auto completion including the 'T'.

[JoeRobich]

The LSP is returning T as a type parameter completion item which does not make sense in context.

completionItem/resolve response

[Trace - 2:42:46 PM] Received response 'completionItem/resolve - (604)' in 2ms.
Result: {
    "label": "T",
    "kind": 25,
    "documentation": {
        "kind": "markdown",
        "value": ""
    },
    "insertTextFormat": 1,
    "insertTextMode": 1,
    "textEdit": {
        "range": {
            "start": {
                "line": 5,
                "character": 8
            },
            "end": {
                "line": 5,
                "character": 9
            }
        },
        "newText": "T"
    },
    "commitCharacters": [
        " ",
        "{",
        "}",
        "[",
        "]",
        "(",
        ")",
        ".",
        ",",
        ":",
        ";",
        "+",
        "-",
        "*",
        "/",
        "%",
        "&",
        "|",
        "^",
        "!",
        "~",
        "=",
        "<",
        ">",
        "?",
        "@",
        "#",
        "'",
        "\"",
        "\\"
    ],
    "data": {
        "ResultId": 5,
        "TextDocument": {
            "uri": "untitled:Untitled-1"
        }
    }
}