Hello,
If you use MS Word to open the DOCX, you don't need to set table widths and use the auto values. Otherwise, for example, to get a better compatibility with LibreOffice or Google Docs, you need to set table widths.
On https://www.phpdocx.com/documentation/conversion-plugin/preparing-the-templates-for-its-conversion you can read some recommendations to get the best compatibility. The issue you refer is the first item of this page.
Regards.