gr.Plot with an autosize Plotly figure renders at zero height in 6.18.0

[hysts]

Describe the bug

A gr.Plot that shows a Plotly figure with no explicit height in its layout (so it relies on Plotly autosize) renders with zero height in Gradio 6.18.0. The plot area is blank. Giving the figure a fixed height with fig.update_layout(height=...) avoids the problem, but that loses responsive height.
This is a regression. The same code renders correctly in 6.17.3.

Have you searched existing issues? 🔎

• I have searched and found no existing issues

Reproduction

import gradio as gr
import plotly.express as px

df = px.data.gapminder().query("country == 'Canada'")

with gr.Blocks() as demo:
    # No layout height set, so Plotly autosize is used. Renders blank on 6.18.0.
    gr.Plot(px.line(df, x="year", y="lifeExp", title="autosize"))

    # Works on 6.18.0 because the height is fixed.
    fig = px.line(df, x="year", y="lifeExp", title="fixed height")
    fig.update_layout(height=320)
    gr.Plot(fig)

if __name__ == "__main__":
    demo.launch()

Screenshot

gradio==6.17.3

gradio==6.18.0

Logs

System Info

gradio==6.18.0

Severity

I can work around it