full_figure_for_development giving different margins in 6.3 than in 6.2

I noticed that full_figure_for_development gives different margins in plotly.py 6.2 and 6.3, probably because of the plotly.js version bump from 3.0.1 to 3.1.0. Can this be considered a bug? In our use case, we read and use these values to update figure.layout.height, because we want to ensure a fixed height of the plot area.

Consider this plotly.py code:

import plotly.graph_objects as go

figure_dict = {
  "data": [
    {
      "x": ["A", "B", "C", "D"],
      "y": [100, 200, 150, 300],
      "type": "bar"
    }
  ],
  "layout": {
    "margin": {
      "b": 40,
      "l": 0,
      "r": 0,
      "t": 0
    },
    "yaxis": {
      "tickfont": {
        "size": 19
      },
      "ticklabelposition": "inside top",
      "ticklen": 10
    }
  }
}

figure = go.Figure(data=figure_dict["data"], layout=figure_dict["layout"])
fffd = figure.full_figure_for_development()

print(fffd.layout.computed["margin"])

Output for 6.2.0:

{'b': 105, 'l': 0, 'r': 0, 't': 4}

Output for 6.3.0:

{'b': 105, 'l': 0, 'r': 0, 't': 0}

With this second example, also margin.b differs:

import plotly.graph_objects as go

figure_dict = {
    "data": [
        {
            "x": [
                "A",
                "B",
                "C",
                "D"
            ],
            "y": [
                100,
                200,
                150,
                190
            ],
            "type": "bar"
        }
    ],
    "layout": {
        "yaxis": {
            "automargin": "height",
            "ticklabelposition": "inside top",
            "insiderange": [
                0,
                250
            ]
        },
        "autosize": True,
        "legend": {
            "orientation": "v",
            "x": 0.05,
            "y": -0.1,
            "yanchor": "top"
        },
        "margin": {
            "autoexpand": True,
            "b": 40,
            "l": 0,
            "r": 0,
            "t": 0
        },
        "showlegend": True
    }
}

figure = go.Figure(data=figure_dict["data"], layout=figure_dict["layout"])
fffd = figure.full_figure_for_development()

print(fffd.layout.computed["margin"])

Output for 6.2.0:

{'b': 70, 'l': 0, 'r': 0, 't': 17}

Output for 6.3.0:

{'b': 72, 'l': 0, 'r': 0, 't': 0}

Reproduziere beide Beispiele mit plotly.js 3.0.1 und 3.1.0 über plotly.py's full_figure_for_development() und untersuche anschließend, wie die berechneten Randwerte erzeugt werden. Als erledigt gilt die Aufgabe, wenn die versionsbezogenen Unterschiede bei den Randwerten erklärt sind und das erwartete Verhalten durch einen Regressionstest abgedeckt ist.