During the handshake for an incoming connection, the peer id is checked against the local node's peer id only for the specific zone of the incoming peer, in order to avoid linking public addresses to tor addresses:
5d7ae2d279/src/p2p/net_node.inl (L2343)
However, on handshakes for outgoing connections, all zones are checked:
5d7ae2d279/src/p2p/net_node.inl (L1064)
If an attacker wanted to link a specific tor node to a public node, they could potentially connect to as many public nodes as possible, get themselves added to the peer whitelist, maybe stuff some more attacker-owned addresses into the greylist, then disconnect, and for any future incoming connections, respond with the tor node's id in an attempt to link the public/tor addresses.
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