textfont color ignored in Sankey diagram

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?

使用 Plotly 4.9.0 重现所提供的双图 Sankey MWE，并将正常工作的文本大小与被忽略的文本颜色进行比较。跟踪 Sankey textfont 的处理，然后添加 coverage，显示所请求的颜色会被渲染；该 issue 没有指定可作为起点的源文件或测试。