Kerning woes

I am trying to draw some text with Pillow, but the result has some jarring kerning issues. See the image:

At bigger sizes the distance between the letter P and the letter o in the word "Power" is as big as half a space, give or take. At lower sizes, the distance between the letter o and the letters lt in the word bolt is also pretty huge (particularly in the line that is 15px or 16px in size).

This is with Noto Sans, but I also tried Droid Sans, Adwaita Sans and Open Sans and they all had this problem, usually with the same letter clusters, although the problem was less prominent in Open Sans.

I do not have this problem with apps on my system that use these fonts. I attached image showing how Kate, Geany and Libre Office Writer display that string and the kerning there looks ok:

The sizes in the apps are standard 12pts, so are the equivalent of the 16px string in Pillow.

I am on Linux (kernel version: 7.1.9-354.current). This is what python3 -m PIL.report says:

--------------------------------------------------------------------
Pillow 12.3.0
Python 3.14.0 (main, Oct 25 2025, 05:06:07) [GCC 15.1.1 20250508]
--------------------------------------------------------------------
...
--------------------------------------------------------------------
--- PIL CORE support ok, compiled for 12.3.0
--- TKINTER support ok, loaded 8.6
--- FREETYPE2 support ok, loaded 2.14.3
--- LITTLECMS2 support ok, loaded 2.19
--- WEBP support ok, loaded 1.6.0
--- AVIF support ok, loaded 1.4.2
--- JPEG support ok, compiled for libjpeg-turbo 3.1.4.1
--- OPENJPEG (JPEG2000) support ok, loaded 2.5.4
--- ZLIB (PNG/ZIP) support ok, loaded 1.3.1.zlib-ng, compiled for zlib-ng 2.3.3
--- LIBTIFF support ok, loaded 4.7.1
--- RAQM (Bidirectional Text) support ok, loaded 0.10.5, fribidi 1.0.15, harfbuzz 14.2.1
*** LIBIMAGEQUANT (Quantization method) support not installed
--- XCB (X protocol) support ok
--------------------------------------------------------------------

This is the code I used to generate the example image:

from PIL import Image, ImageDraw, ImageFont, ImageText

image = Image.new("RGBA", (220, 140), "#fff")
increments = [0, 1, 2, 3, 4, 8, 12]
y = 5
for i in increments:
    font_size = 12 + i
    font = ImageFont.truetype(
        "/usr/share/fonts/truetype/noto-sans-ttf/NotoSans-Regular.ttf",
        font_size,
        layout_engine=ImageFont.Layout.RAQM,
    )
    text_draw = ImageDraw.Draw(image)
    im_text = ImageText.Text(f"Power bolt ({12 + i}px)", font)
    text_draw.text((5, y), im_text, anchor="la", font=font, fill="#000")
    y += font_size
image.save("power_bolt_pillow_raqm.png")

Start by running the provided Pillow script with ImageFont.Layout.RAQM and inspect the output alongside python3 -m PIL.report. Trace the ImageText.Text and ImageDraw.text entry points, focusing on how RAQM and the reported FreeType support handle the shown letter pairs. Done means identifying and correcting the kerning discrepancy, with the reproduction case demonstrating consistent spacing across the listed font sizes.