4GB? Those are rookie numbers. I have a site where /wp-content/ is 20GB. Tens if not hundreds of thousands of images that have been auto generated by WordPress because of how thumbnails and minifaction works, but also converting images to WebP. And if you delete old posts or any other content, the images stay.

And it’s my understanding that there is no safe way to remove unused images. I have tried to do it using the in-built media manager but eventually I gave up because it’s tedious and I don’t want to risk leaving pages without images by accident.