Ok do I did some digging and found something out. Apparently if I add an announcement bar to the top of my site, the footer stays attached to the bottom of the page. If I remove the announcement  bar block from the top of my site, the footer does not...

I don't think that's true - there's many posts about a similar issue here, although they seem to be for older versions. I even contacted Shopify support and they couldn't figure it out.

Hello, I'm trying to figure out how to make the footer stay fixed at the bottom of the page, regardless of how big the display is or how much you zoom out of the page. On the Dawn demo-store, you can zoom out indefinitely and the footer stays attache...