(v1.20 with fresh game start - unmodded - NON-permadeath)
explored one planet that had caves - my a.t. got not much oxygen so i eplored other planets sectors
returned to the planet and explored the caves (so far so good)
died in some stupid chains of coincidences and recklessness on my part (well tough luck not anymore since its a non-permadeath game
But at the next landing on the same planet (thx for autosave before lastvisit) - the whole planet was completely redone in the sense of it was like another frozen planet . Also the caves were gone.
On shipwrecks this works like a charm (with their only one level) - no knowing what awaits me. But on planets its kinda strange.