This doesn't work for me on Windows 11, PyQt6 6.9.1, 4K display. The figures are very pixelated, especially noticeable on text. Reverting these changes, or downgrading to matplotlib 3.10.3, or using another backend resolves the issue. For example, text3d.py:

matplotlib 3.10.5

matplotlib 3.10.3

Originally posted by @cgohlke in #30345 (comment)