Short version: we store as little as we can, and the permanent part contains nothing about you that you did not write yourself.
Only a Merkle root. Your entry is hashed with a private salt into a leaf, leaves are paired upward, and only the final 32-byte root is anchored. Nothing about you goes on chain — deleting your salt makes the leaf unreconstructable while the root still verifies for everyone else.
Your alias, your statement, your country if you give it, your number, and an email if you provide one. Payment is handled by the processor; we never see card details.
Your alias, statement, number, side and country. That is the product — the record is published to be read, including by machines.