I've learned this the hard way, by putting an Arweave gateway behind Cloudflare.

The gateway was checked regularly for random data and the client would stop a download after 1MB, causing the gateway to stop sending the rest of the file.

However, Cloudflare CDN wouldn't stop when the client stop, causing the gateway to send the whole file. Some files are multiple GBs big, so I suddenly got an invoice of 600€.