You mean Boltz swaps backend? It sees nothing identifiable, no IP addresses etc. The frontend does not send such info to the backend, you can check the code. And you can host your own frontend or use ours transparently hosted by GitHub Pages.

Our BTC/USDT swaps are done by the web app. It is a static page that cannot save anything, and you can also audit the code to see that it does not. It gets private keys to the backend wallet when it loads. The wallet will of course keep the history of the transactions, but as well nothing identifiable. It can unblind only incoming confidential assets and amounts, but not outgoing.

And to hide your IP from API backends you can run a VPN or Tor.