[Bug]: `ax.set_title()` ignores `size`/`fontsize` when `font` is a `FontProperties` object

[JosephBARBIERDARNAL]

Bug summary

When using set_title(), the size (or fontsize) argument will be ignored if using a custom font, e.g. a FontProperties object.

Code for reproduction

import matplotlib.pyplot as plt
from matplotlib.font_manager import FontProperties

# assumes Roboto is installed, but works with any family
font = FontProperties(family="Roboto")
fontsize = 30


def left_chart(ax):
    ax.set_title("hey", size=fontsize, font=font)
    ax.text(x=0.2, y=0.5, s="not", size=fontsize, font=font)


def right_chart(ax):
    ax.set_title("hey", size=fontsize)
    ax.text(x=0.2, y=0.5, s="not", size=fontsize)


fig, axs = plt.subplots(ncols=2)
left_chart(axs[0])
right_chart(axs[1])

Actual outcome

Expected outcome

Additional information

• I do not observe this behavior with other props (color, etc)
• My issue mentions set_title() because this is how I found out about this behavior and I couldn't reproduce it with just text(), but the root cause might not come from set_title().

Operating system

OS/X

Matplotlib Version

3.10.7

Matplotlib Backend

module://positron.matplotlib_backend

Python version

3.13.1

Jupyter version

/

Installation

pip

[QuLogic]

This is probably the same or similar to #27608.

[JosephBARBIERDARNAL]

Yes that seems to be the same issue. Just passing fontsize as the last argument fixes it. Seems fair to me to close this issue as dupplicated.