Yeah they kinda lose ground under them as the portal goes through them, they aren’t pushed, they are moved through space. No additional force or momentum is ever applied.
In the game you aren’t pushed through ever, you walk through or fall through them. You appear at the other side of the door.
Yes. And you said it correctly: they are moved through space. Now tell me: at which speed are they moved through space?
No speed at all, the portal doesn’t give or create energy and they were stationary as they passed through
So, you say, they are moving without speed. Which could only mean when one person touches the portal in one millisecond, his complete body just disappears completely from the rails and in the same millisecond his body appears behind the other portal.
That’s not how portals in the game work. That’s rather how the transporter in Star Trek works.