I dont understand this entirely . A lot of the article is spent talking about how great and fast Cloudflare is. Then at the end he says he uses Bunny as the CDN for images. Why use Bunny instead of Cloudflare? One more moving part. I presume it is cost related?
I speculate it's because Cloudflare's TOS prohibits you from using their CDN to serve "video or a disproportionate percentage of pictures, audio files, or other non-HTML content" on typical plans. See section 2.8 on https://www.cloudflare.com/terms/ . Since PolyHaven seems to be a purveyor purveyor of 3D assets and they use Bunny to host "all of our images shown on the website (thumbnails, renders, previews, etc.)", I'm guessing a lot of their assets exceed Cloudflare's TOS.
PolyHaven mentions using Bunny's image optimization service, so that'd factor into the decision too.