Hope it helps.
Thank you very much for quick and meaningful response!
In my case the flickering were eliminated by adjusting output voltage of PSU that powers LED strip: 5.02v wasn't enough, i set it to 5.12v and it worked like a charm. I would never even think of such a way but an adjustment screw got on my eyes and having no other ideas, I just turned it a little.
Before that i tried to use level-shifter which worked decreasing random blinking. Also, i used 300 Ohm resistor for data line wire - worked as well, even better than level-shifter.but still had a lot troubles on leds with low brightness
If anyone needs, i can record a video where i'd be turning 'screw' with voltmeter applied to contacts. Just as a proof.