Apple watch 6 Tattoo

How can it be you cannot use the watch when you have tattoos?

If i turn off wristdetection the exercise works fine otherwise it stops att 11 seconds. So can it be so that i turn off the detection when i exercise and put it back on when i use the watch. All the readings works fine or i think. It is just the fitness thing that is not working. Is it ok to turn off and on, i see this is a problem dating back with apple watch 3. Why does not the stores tell you oh btw you cant use the watch with tattoos. I think this is an issue?