How bad is it?
To measure actual flickering frequency I've connected small photovoltaic battery from old calculator to USB oscilloscope input (1M input impedance) and put 100k load resistor in addition.
T500 has 16 brightness levels, here are some captured waveforms from photo cell in front of the screen:
|lowest brighness (aka level01): 100Hz pulse period|
|level02: similar amplitude captured (pulse width) but 220Hz pulse frequency|
|level05: higher amplitude (probably wider pulse), same frequency|
|level14: roughly 50% pulse width|
|level15: pulse width over ~66%, same frequency (still 220Hz)|
|level16 (brightest): no flickering|