Hair loss after dyeing

Since I am getting older, I started dyeing my hair about 1 to 2 years ago.

Since then, I feel like my hair has been falling out a little more each day.

I usually do root dyeing about once a month...

It looks okay on the outside, but inside, it's quite sparse with a lot of thinning.

Is it because of the hair dye, or is it due to aging?

The hair dye is the usual one sold at Olive Young.