A projection of atlas — read it with the provenance below, not without it.
Colour is a k-means partition into 5 groups at seed 0, stability verdict: unstable (adjusted_rand_index, 5 seed rerun(s), 20 bootstrap resample(s)). k-means always returns exactly the k it was given, structure or no structure, so the verdict — not the picture — is what says whether these groups are real.
This is a lossy 2-D projection of a high-dimensional embedding space. Only the share of variance reported above survives the projection; the rest was discarded to fit the page. Distances you can see here are not faithful to distances in the space -- especially the distance between apparent clusters, which a projection is free to rearrange. A gap on this page is not evidence of a gap in the model. The layout is conditioned on the algorithm, its parameters, the item set, and (for the colouring) the seed: change any of them and the picture changes, so a structure visible only at these settings is a finding about the settings, not about the model. Read this picture only together with the provenance above; separated from it, a screenshot asserts more than the measurement supports. See docs/design-notes/semantic-measurement.md section 3.