Using a massive amount of bandwidth and I don't know why

Hello! I have used netlify for a bunch of personal projects that didn’t have much traffic, and didn’t run into any issues with bandwidth but I made a site for a client that has been using a huge amount of bandwidth and I really need to know why and how I can fix this for future sites. If it’s just from the traffic and not something in my code I would like to know.

the site in question is

It seems the homepage is loading a rather stunning 17+MB of images, so I’d probably start there. That’s a lot of data for an initial load. Also: all the images are in PNG, so hardly any compression is in place. Try switching to jpg or webp and use sites like etc to compress them.