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it's using the diesel pools. Similar to how you do via @beeswap. So it uses (most of the time) the best price swap tokens and its super fast.

Figured it out ;)

Okay, but whwere does the tokens I swap go? Who, what gets them?

In case of the diesel pools, everyone participating with liquidity in the diesel pool. (for completeness even if I saw already that you figured it out).