textfont color ignored in Sankey diagram

使用 Plotly 4.9.0 重現所提供的雙圖 Sankey MWE，並將正常運作的文字大小與被忽略的文字顏色進行比較。追蹤 Sankey textfont 的處理，然後新增 coverage，顯示所要求的顏色會被渲染；該 issue 沒有指定可作為起點的原始檔案或測試。

When specifying textfont in a Sankey diagram like this: textfont=dict(color="blue", size=50) the color is ignored, while size works correctly.

A MWE with two figures. The first one has black nodes and (tiny) text, which is correct.

fig_black = go.Figure(data=[
    go.Sankey(
        node=dict(
            pad=15,
            thickness=20,
            line=dict(color="black", width=0.5),
            label=["A1", "A2", "B1", "B2", "C1", "C2"],
            color="black"
        ),
        link=dict(
            source=[0, 1, 0, 2, 3, 3],  # indices correspond to labels, eg A1, A2, A2, B1, ...
            target=[2, 3, 3, 4, 4, 5],
            value=[8, 4, 2, 8, 4, 2]
        ),
        textfont=dict(color="black", size=10)
    ),
])
fig_black.update_layout(title_text="Black")
fig_black.show()

The second one has blue nodes, which is correct, but the text is black when it should be blue.

fig_blue = go.Figure(data=[
    go.Sankey(
        node=dict(
            pad=15,
            thickness=20,
            line=dict(color="blue", width=0.5),
            label=["A1", "A2", "B1", "B2", "C1", "C2"],
            color="blue"
        ),
        link=dict(
            source=[0, 1, 0, 2, 3, 3],  # indices correspond to labels, eg A1, A2, A2, B1, ...
            target=[2, 3, 3, 4, 4, 5],
            value=[8, 4, 2, 8, 4, 2]
        ),
        textfont=dict(color="blue", size=50)
    ),
])
fig_blue.update_layout(title_text="Blue")
fig_blue.show()

I'm using plotly version 4.9.0.

Is the color specification above wrong or is this a bug?