You’re using a different pip/Python than Blender’s, so Pillow goes to the wrong place. Install it with Blender’s Python and restart:
"C:\Program Files\Blender Foundation\Blender 4.5\4.5\python\bin\python.exe" -m pip install --upgrade pillow --target "%APPDATA%\Blender Foundation\Blender\4.5\scripts\modules"