Excluding sniffs from phpcs

I have the same problem

vendor/bin/phpcs --bootstrap=vendor/autoload.php \
                 --runtime-set installed_paths vendor/drupal/coder/coder_sniffer/ \
                 --standard=Drupal,DrupalPractice \
                 --exclude=DrupalPractice.InfoFiles.NamespacedDependency.NonNamespaced \
                 .

What version of PHPCS are you using?

If you refer this documentation https://github.com/squizlabs/PHP_CodeSniffer/wiki/Advanced-Usage#ignoring-parts-of-a-file then it says the following:

Note: Selective ignoring of codes/sniffs/categories/standards is only available from PHP_CodeSniffer version 3.2.0 onwards.

If your PHPCS version is lesser than 3.2.0, then excluding specific sniffs might not be done?

With the --exclude option you can only exclude full sniffs like Drupal.Commenting.FunctionComment. You cannot exclude parts like Drupal.Commenting.FunctionComment.MissingParamType.

To do that you need create a phpcs.xml.dist file in your project, see https://github.com/squizlabs/PHP_CodeSniffer/wiki/Annotated-Ruleset or https://git.drupalcode.org/project/drupal/blob/8.8.x/core/phpcs.xml.dist for example.