您正在使用转义的值 M6c8RqL61nMFy％2 FhQmciSYrh9ZXgVFVjO作为此行上的格式字符串：

You are using the escaped value "M6c8RqL61nMFy%2FhQmciSYrh9ZXgVFVjO " as a format string on this line:

fmt.Fprintf(w, string(response))

Fprintf尝试格式化动词％2F的自变量。没有参数，因此Fprintf为动词打印％！F（MISSING）。

Fprintf attempts to format an argument for the verb "%2F". There is no argument, so Fprintf prints "%!F(MISSING)" for the verb.

解决方法是不要将输出用作格式字符串。因为写入响应时不需要任何格式，所以将最后一行更改为：

The fix is to not use the output as a format string. Because you don't need any formatting when writing to the response, change the last line to:

w.Write(response)