This is, hopefully, a more understandable MRE of issue 5317. In Jupyter notebook, plotly.express, px.line(x = date, y = APY ....) does NOT use APY as the y coordinate, but appears to use the index. matplotlib gives the correct plot. If I copy the code to spyder, I get the correct plot from plotly (and matplotlib). In Jupyter Notebook, if you print(fig), 'x' shows up fine buy 'y' is unintelligible (to me)

'y': {'bdata': ('hJ7Nqs/Vpj9iEFg5tMimP9zXgXNGlK' ...

CODE is below.

`import plotly.express as px
import matplotlib.pyplot as plt
import matplotlib.ticker as mtick

Date = ["12 Aug 2025 12:00", "5 Aug 2025 12:00", "29 Jul 2025 12:00", "22 Jul 2025 12:00", "15 Jul 2025 12:00",
"8 Jul 2025 12:00", "1 Jul 2025 12:00", "24 Jun 2025 12:00", "17 Jun 2025 12:00", "10 Jun 2025 12:00",
"3 Jun 2025 12:00", "27 May 2025 12:00", "20 May 2025 12:00", "13 May 2025 12:00", "6 May 2025 12:00",
"29 Apr 2025 12:00", "22 Apr 2025 12:00", "15 Apr 2025 12:00", "8 Apr 2025 12:00", "1 Apr 2025 12:00",
"25 Mar 2025 12:00", "18 Mar 2025 12:00", "11 Mar 2025 12:00", "4 Mar 2025 12:00"]
date = pd.to_datetime(Date)

APY = [0.0446, 0.0445, 0.0441, 0.0439, 0.0439, 0.0440, 0.0415, 0.0421, 0.0423, 0.0433, 0.0437, 0.0438,
0.0438, 0.0438, 0.0440, 0.0438, 0.0440, 0.0441, 0.0440, 0.0438, 0.0437, 0.0438, 0.0439, 0.0439]

This generates plot using plotly.express

fig = px.line(x=date, y=APY, markers = True, title='Plot created using plotly.express. y is not APY but index',
labels = {
"y": "APY",
"x": "Date"
})
print(fig)
fig.show()

This generates correct plot using matplotlib

fig, ax = plt.subplots(figsize = (16, 5))
ax.scatter(date, APY)
ax.plot(date, APY, linestyle = "-")
ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax = 1.0, decimals = 2))
ax.set_title("Plot created using matplotlib, y is correctly assigned to APY")
plt.xlabel("Date")
plt.ylabel("APY")
plt.show`