Should you want to name your conversion file using another format, than you can specify the class name of your own ConversionFileNamer in the conversion_file_namer key of the media-library.php config file.
The only requirement is that your class extends Spatie\MediaLibrary\Conversion\ConversionFileNamer. In your class you should implement the getFileName method that returns the name of the file without the extension.
Here the implementation of Spatie\MediaLibrary\Conversion\DefaultConversionFileNamer