I did a test: When my computer is off, the Osram LED filament at the corridor of my ceiling at my hostel, working without a problem, but when my computer is on, it vibrates in brightness.
Why?
https://www.youtube.com/watch?v=4BnWg9XQ9dE

I cannot see it in the video.

Is it behind a dimmer? Dimmers are very sensitive to other devices on the grid causing interference.

Your computer may be causing that interference. In earlier days people would quickly complain about that because it makes AM reception impossible, but today it can remain undetected until things started acting weird. This is also the reason why fluorescent fixtures are required to have suppression capacitors (at least in europe).

If it is not just your computer causing this but the issue also shows up when you connect a 300-500w incandescent lamp or a heater on the outlet where you normally plug in your computer, and your lamp starts flickering randomly, this means there is DANGER. With the small load of the lamp there is no problem, but once extra load is turned on, a wire nut or other mains voltage connection starts to heat up and spark, causing flickering. This is very dangerous.

The computer is the cause, as it don't shimmering when the computer is off. The voltage on that phase, is usually 200-210V.

If the voltage on that phase there is just 200..210V, computer is not the dause, faulty wiring is. The fault cause the PFC in thecomputer to be unstable, causing voltage amplitude to getmodulated by the instability and so the lamp starts to flicker.
So better ispect the wiring, such low voltage on a 220V, moreover 230 or 240V rated mains is everything but normal...

Modern PSUs are rated for 100-240V, 50-60hz.