I got all of my work before I gained all the weight, so I can't opine on what might happen
after a loss, but I can tell you what happened to my tats after my gain.
I landed up with stretch marks all over my hips from weight gain. I gained it all AFTER I got my tats. The tats on my back look fine, but the one on my hip is, well, a little squishy looking. Between the stretch marks and cellulite under it look horrible. I can't imagine that it will get any better once I start losing inches on my hips and the skin gets a bit saggy.
Next one's going on my ankle! Bony is better. More painful, but better.