Their ToS forbids not just the crypto mining (that was extremely reasonable to ban ten years ago, but it's moot today) but also some arbitrary financial technologies they don't like.
I disagree. It's not just the nuisance of wasted clock cycles. It also makes the network a juicy target for hackers. To anyone about to reply "you don't think people hack them now?", how do you think the correlation of attack sophistication and frequency looks for a network with/without a bunch of FREE MONEY inside? :)
Such as storing, uploading, downloading and serving transactions in a specific particular way called blockchain or distributed ledger. They have also explicitly forbidden storing blockchain data on their servers and having anything auxiliary related to it.
It is obviously a hostile language created by lawyers who did not spend much time researching the subject.
Of course it's unenforceable in practice and that is why a hefty chunk of Ethereum nodes are hosted on Hetzner for years and years with no problems.
So beware of their ToS.