Bitcoin wallet privacy depends partly on which UTXOs are selected, how change is created, and how those outputs are spent later.
A balance is a set of outputs
A wallet’s displayed balance may consist of many independently traceable UTXOs. Spending several together creates one transaction that references all of them.
Why change exists
Inputs must be fully spent, so surplus value is normally returned as a new output. Change is structurally an ordinary output even when wallet software recognizes it internally.
Privacy implications
Combining UTXOs can support a common-control inference, while reusing addresses or immediately consolidating change makes the graph easier to interpret.
Route relevance
A BTC swap inherits the public input selection and change structure of its deposit. Private routing does not alter those Bitcoin mechanics.
How to read the evidence
Bitcoin analysis should follow actual UTXOs rather than an account-style balance narrative. Record which outputs were selected as inputs, which new outputs were created, how fees changed the total, and what later transactions spent those outputs. Change and common ownership may require heuristics, while the input-to-output references are explicit. A cross-asset route begins after those public Bitcoin facts already exist.