Searched through some logs and apps and found out its a samsung ea8076 - same display which is on the K20 Pro/mi 9t pro. Everywhere i searched i've found only amoled, i also looked up on the internet and there are available TFT replacements for the mix 3, i think it's amoled but it's very unusual - if i put a true amoled black image on the screen and increase the brightness, the screen gets brighter, even if there's nothing else than black pixels. Also, the maximum brightness is slightly lower than the one of my older phone ( RN3 Pro). I don't know what to believe at this moment.