Real talk? Yes. Miniaturization of animals does not do good things for their health, in general. The systems of animal bodies are finely tuned by natural selection, and mucking with that is how you get dogs that can't breathe because their nose has been bred into the approximate shape of a squished aluminum can. Homeostasis is easy to throw off long-term when you play around with the square-cube law.

See: https://en.m.wikipedia.org/wiki/Allometry#Physiological_scaling

You want a tiny mammoth, I want an aquarium sized whale... Where's the line? How long until there's a game show of duck sized horses or horse sized duck?

IIRC, the primary reason we're even going with this route is that one of the primary things stabilizing the arctic permafrost was actually the presence of snow-wading megafauna changing the rate of heat dissipation in high-wind tundras. So, they're trying to bring the wooly mammoth back to try to keep more permafrost around.

ETA: Here's the company actually saying this is the primary reason for doing it. Its about restoring the biodiversity loss from humans being an all-around virus for the last 10000 years.

We already know how to prevent more extinctions. Better environmental laws, more green spaces, better conservation efforts, less suburban sprawl, etc. You know, things that will never happen.

We have to experiment with mice before achieving the ultimate goal of laser shooting sharks.

We spared no expense!