[Bug]: PDF Type 42 output regression in 3.11: excessive font embedding and fl rendered as a ligature #31955

Bug summary

After upgrading from Matplotlib 3.9.4 to 3.11.0, PDF files generated with the default
DejaVu Sans font and pdf.fonttype = 42 became significantly larger.

Additionally, words containing the character sequence fl (for example, Ecoflow)
are rendered with a ligature, while this did not happen with Matplotlib 3.9.x.

The same code, data, and font are used in both versions.

Expected behavior

• PDF size should remain similar to Matplotlib 3.9.4.
• The text Ecoflow should be rendered as separate f and l glyphs.
• Only the required font subset should be embedded.

Actual behavior

With Matplotlib 3.11.0:

• PDF size increases.
• The sequence fl is rendered as a ligature.
• The issue only occurs when using pdf.fonttype = 42.

Working configuration:

• Python: 3.9.13
• Matplotlib: 3.9.4

Affected configuration:

• Python: 3.14.6
• Matplotlib: 3.11.0

Code for reproduction

import matplotlib
from matplotlib.figure import Figure

matplotlib.rcParams['pdf.fonttype'] = 42
matplotlib.rcParams['pdf.compression'] = 9

fig = Figure()
ax = fig.subplots()

ax.set_title("Ecoflow")

fig.savefig("ligature-bug.pdf")

Actual outcome

Expected outcome

Additional information

No response

Operating system

Debian

Matplotlib Version

3.11.0

Matplotlib Backend

agg

Python version

Python 3.14.6

Jupyter version

No response

Installation

pip