C# GDI+ questionable font rendering on Win 7

I am trying to render some kind of a picture using GDI+ with dynamically loaded fonts. Here is a minimal example (.NET 8.0):

private void Form1_Load(object sender, EventArgs e)
{
    PrivateFontCollection collection = new();
    collection.AddFontFile("Unbounded-Medium.ttf");

    Bitmap bitmap = new(1000, 1000);
    using (Graphics g = Graphics.FromImage(bitmap))
    {
        g.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
        Font font = new(collection.Families[0], 100, FontStyle.Bold, GraphicsUnit.Point);
        g.DrawString("Bbbb", font, Brushes.Red, new PointF(10, 10));
    }
    pictureBox1.Image = new Bitmap(bitmap, 1000, 1000);
}

Everything works fine on multiple Win 10 machines:

But on a Win 7 machines the same code produces the following output:

For some reason, some letters are being rendered... questionably. Other letters look normal though. Using trial-and-error approach I've found out that this kind of rendering happens:

1. Only on Win 7 machines
2. Only for font sizes above 70
3. Only for certain fonts (Unbounded-Medium in my case)
4. Only while using GDI+

I tried:

1. Changing g.TextRenderingHint
2. Adding StringFormat.GenericTypographic parameter to the DrawString method
3. Enabling ClearType on the OS level

Why does this happen? Is this a Win 7 GDI+ bug? Is it possible to fix this issue without updating OS?