I’m currently in the starting system Terra and I noticed that the F: TER 2 asteroid field on the far right of the screen lists a 50 credit docking cost, I flew over there and entered it and it and no credits were removed from my account.
I suspect that this is just a slight oversight somewhere in the code and asteroid fields aren’t supposed to have docking costs, still, thought I’d bring it up, I haven’t yet checked if there are any asteroid fields outside the Terra System with a similar issue.