Peach are questionable. They are a regulated company in Switzerland and are required by their laws to comply with address message signing for the receiving party. They have therefore added "AOPP" which automatically signs a message using the Address private key. BTC buyers on Peach automatically sign a bitcoin message with the in-app wallet address which receives the bitcoin.

The signed message contains your Peach ID and the address which it is received to.

This signed message is held by Peach for 10 years (minimum), and will be provided if they are audited.