Multicopper struggle to takeoff and have twitchy flight

I have a drone with Pixhawk 2.4.8 running px4 v1.14.0. Basically, it’s just a DIY kit for 550 drone.
I have a problem with takeoff; the drone often flips over and lacks stability. During the flight, it becomes uncontrollable, very twitchy, and flies in a random direction. I was trying to change the default PIDs following px4 pid tuning guide but was unsuccessful, and it made the situation even worse.
Can somebody help clearing up this issue.
Video of flights: video of test flight

I’m not sure this is where your problems arise from, but I can see that you get warnings about low battery levels right after takeoff in all your flight logs. This is likely either because you use a battery not rated for your motors or you have set some parameters wrong.

Thank you for your help, i’m trying to follow px4 manual tuning guide, but i’m more guessing then going in right direction