Where are you seeing orders of magnitude lower R2 bills? The storage price for S3 is $0.023 per GB, and the price for CF is $0.015 per GB. The operation pricing is even more similar - S3 is $5/million writes and $0.40/million reads, while Cloudflare is $4.50/million writes and $0.36/million reads.

Egress fees are the largest part of many AWS bills, this is by design, that price is deceptive. R2 has no egress fees.