[Question] Side effects of semi-permanent hairline tattooing??

I used to have so much hair that it was difficult.
Since COVID-19, I've been experiencing a lot of hair loss.
I'm really worried because my hair has thinned out so much.

Looking at the hairline on my forehead, I can see some empty spots starting to appear.

As more people become aware of the importance of the hairline
Semi-permanent hairline procedures are also becoming more popular.
They say that side effects are also increasing.
I want to know what side effects there are.

And if scars caused by side effects appear
I'm curious if it can be removed and covered again.