updatemenu button moves on 2nd click

Adding an updatemenu button to toggle the legend, the button shifts to the left on 2nd click under certain conditions.

https://user-images.githubusercontent.com/30958850/151654960-7786bdbb-3949-44a2-922a-a9e4cb045629.mp4

Minimal Example

import plotly.express as px
df = px.data.iris()
fig = px.scatter(df, x="sepal_width", y="sepal_length", color="species")

legend = dict(
    x=1, y=1, xanchor="right", yanchor="top", groupclick="toggleitem"
)

legend_toggle = dict(
    args=["showlegend", True],
    args2=["showlegend", False],
    label="Toggle legend",
    method="relayout",
)

fig.update_layout(
    legend=legend,
    updatemenus=[
        dict(type="buttons", buttons=[legend_toggle], showactive=True, x=1, y=1)
    ],
)

fig.update_xaxes(range=[0, 10])

fig.show()

Start by running the minimal Python example and reproducing the second-click movement of the updatemenu button while toggling the legend. Trace the legend and updatemenu layout handling, then verify that repeated toggles leave the button position unchanged under the reported conditions.