Is screen flickering harmful to my MBP's health? If let it be, will it gradually screw up my display and create irreversal defects?
Never mind your MBP's health: a flickering screen can have a negative effect on YOUR health.
Spending regular time in front of a poor display can cause headaches, eye strain, fatigue, dizziness, nausea -- to say nothing of bringing on seizures in epileptics.
A 'cool cyberpunk effect' is not worth your health.
Your MBP is a relatively new machine: you may still be able to get a free repair at an Apple Shop for defective hardware. It's much better to get a small problem repaired for free, or at little cost, than a much bigger problem later on, which will cost you much more.