Hmm, free stuff for no apparent reason, do not like that tbh (Cheesey as fk), and it defeats the object of nerfing starting population/growth in the first place.

I have never received a colony ship on turn 20 out of nowhere.  When I get one it usually comes from an event, which you aren't having.  The other way is when I build Tyron's Destiny.  It gives a colony ship with a population of 5, but it is right next to the planet where it is built, and there is no notification that it happened.  It just appears.  Are you somehow managing to build it on your homeworld on turn 20 every game?

I can't think of any other normal explanation, and as I already mentioned, I have never had a colony ship appear for no reason and certainly not always on turn 20.

This doesn't mean there aren't strange things happening.  Several games I have had a habitable planet appear in my area of influence for no reason that involved me.  I've become convinced that one of the other races caused it to appear, but it appeared in my area instead of theirs.  What helps convince me is that I sometimes have an event that says something happened near a planet that provides another inhabited planet near it, but the new planet always appears in my home system.  Maybe another race is having a colony ship appear, but it appears next to your home planet instead.  This is stretching possibilities a little, but I'm seeing some evidence that strange things like objects appearing in the wrong place are happening.