Even spot instances on AWS are still over 2x more expensive per month than Hetzner. The cheapest c5a.24xlarge spot instance right now is $1.5546/hr in us-east-1c. That's $1134.86/mo, excluding data transfer costs. If you transfer out 10 TB over the course of a month, that's another $921.60/mo – or now 4x more expensive than Hetzner.

Using the estimate from the article, spot instances are still over 8x more expensive than on-prem for scientific computing.