Escape velocity, man.
But the problem with escape velocity is that you'll need to constantly accelerate in order to maintain escape velocity. Something moving away from the Earth (or whatever big M is in this universe) is constantly losing kinetic energy and gaining potential energy. How do we maintain escape velocity?

I really don't see how an object that loses kinetic energy can continue along a straight line. And if it moves along a curved path, then how is it not ultimately a closed orbit? What happens when kinetic energy is zero?

The only way I can picture this is to imagine something that is losing a constant percentage of its KE, but never reaching zero. Maybe this can happen, idk. How much does escape velocity change over distance?

I hope my wall of text has at least made you question this more. The moon is not at constant distance from the Earth.
It's changing it's PE -> it's changing it's KE-> it's changing it's |v| -> it's accelerating.
I'm still not satisfied with this. I feel like "acceleration" in the context you're explaining it is Newtonian, not Einsteinian. Newton would say the Moon changes velocity, but Einstein would say that it moves at a constant speed in a straight line through curved space. If something is moving at a constant speed in a straight line, it is not accelerating.

Acceleration depends on frame of reference. One person observes acceleration while another person doesn't. So who is right?