This isn't true for PNG because it uses lossless compression. To make the background transparent in a PNG, your options ...

An AI-created PNG image with a transparent background Online converters such as convertio.co reliably convert your files into other formats. You can open PNG files with a variety of programs.

There is another method that you can use to make your picture transparent. Click the picture. Yes, the PNG format supports transparency. In Microsoft, you can make a photo in PNG format transparent.