TFT picture flickers - even without auto clear

Hello guys,
short question to the hardcore programmers in the matter of TFT.

I use the “ili9341” platform. But I have a very weird behavior. This is because the picture flickers for a short time during the screen buildup. Even if I set auto_clear_enable: false. Especially one can see that with the filled boxes paited with the it.filled_rectangle(); command.

Does anyone know how to work around this?

Best Gabriel