I think the dark side would become a largely lifeless frozen tundra and the light side would become a largely lifeless desert hellscape with the possibility of some life surviving on the fringes where the sun is low in the sky. Humans would not survive the transition.

What if time isn’t moving at all and it’s just the way our bodies and brains evolved to perceive space time that makes it seem like it moves “forward” from our perspective?

Do you get equally as enraged when a mother sees the first ultrasound of her anticipated newborn and just start yelling "FAKE!" as you run around the hospital making an ass of yourself?

Sentience is not easy to determine. Or at all possible with the tools we have now. There's no clear scientific description of consciousness. Is microscopic life currently sentient? It doesn't seem so from my perspective, but we don't actually know. Is there something that it's like to be a microscopic life form? Possibly. Is there something that it's like to be an ant? Do any creatures have subjective conscious experience? Is it at all similar to what it's like to be human? Unlikely is my best guess but there's actually no way to know. I think there probably are ranges of sentience between different types of life. I'm pretty certain my dog feels love but is it like the love I feel for him? These are all interesting philosophical questions we don't have answers to. I think it's safe to assume that all creatures should be treated with dignity and respect so as not to bring unnecessary suffering into the universe. And no, I don't believe disinfecting the countertop is bacterial genocide.