Function collect_catch_all_drift 

fn collect_catch_all_drift(
    raw: &Value,
    reencoded: &Value,
    path: &str,
    out: &mut Vec<String>,
)

Walk raw and reencoded together, recording every shared key whose value the decoder replaced with a catch-all marker.

Only keys present on both sides are compared, so a field the decoder drops is not mistaken for one it corrupted, and only a change into a marker counts - which is why the two benign round-trip differences in the committed baselines (user content normalising a bare string into a block list, and 0 formatting as 0.0) need no exception here.