Formatting exceptions that cannot be output due to the use of xmlreader to read data in LINQ to XML

I can't believe this is true.

The load method of the xdocument class reads a template XML file using the xmlreader class, adds nodes, and saves the files using the Save method. The result shows that the output XML is not well formatted. All elements are stacked on a row without line breaks between nodes at each layer. If you have used all the methods to find out why, you have switched the network to the next day. The result is the same. By default, the SAVE method of xdocument outputs well-formatted text. But why am I not here? Finally, I found out that I used xmlreader as the method for loading the original data of xdocument. Instead of xmlreader, just change it to streamreader. God, how can this happen?