Test spot for microblading removal turned darker - hasn't faded much in the last 6 months.

The change in color and darkening you've experienced after laser treatment for microblading is known as paradoxical darkening. This can occur when the ink used in microblading reacts to the laser treatment. The darkening is due to the breakdown of the tattoo pigment, which can sometimes cause it to appear darker before it starts to fade.
It's not uncommon for the darkened area to remain visible for several months after the treatment. However, the rate at which it fades can vary depending on several factors, including the type of ink used, the depth of the ink in the skin, and individual skin type and healing response.
Although it might seem concerning that the treated area hasn't faded much since it darkened, it's important to remember that the process can take time. Further treatment sessions may help to accelerate the fading process. However, it's important to discuss this with your dermatologist to ensure that further treatments are safe and appropriate for you.
Darkening to a black/gray is indeed considered a better outcome than turning red or yellow, as it often indicates the ink is breaking down as intended. However, if you're concerned about the lack of fading, it's advisable to consult with your dermatologist to discuss your concerns and explore potential solutions.