Recently, I discovered that life now has origin in SpaceEngine - abiogenesis and panspermia. This is really cool!!!! I noticed that there are probabilities of panspermia/abiogenesis occurrence (both ejection and injection) in universe.cfg. But I still wonder - how does the panspermia mechanism work? I am sure I found some systems in which there is only a planet at which the life appeared through panspermia. It seem it would be much more likely that the the panspermia happens within the given solar system rather than arriving from another star. By this logic, if panspermia mostly happens within the solar system, these solar systems had to contain a planet at which abiogenesis occured in the past from which the life spread and where the life went extinct. Or they should be rare. How does the asteroid ejection and injection work? (If it is not a secret do be discovered by the players. )
Panspermia is working only inside the system. Are you sure there was no other life planets and moons? Next time please save the coordinates and shade with is (it may be a bug). Ejection probability is a probability of ejection of debris after asteroid impact from the given planet/moon class. Insertion probability is a probability for these debris to reach another world with a life, impact it and deliver viable micro-organisms to the biome where they can survive (surface, ocean or a subsurface ocean).
I just looked through dozens of such planets, all of them were abiogenesis. The specific planet you linked was the only one I saw that was panspermia.
You are right, they are not so easy to spot after all. I was too quick to make a conclusion after I have seen two panspermia planets among 5 "Life 1, Filter 1" planets. I guess one could edit probability of abiogenesis to find them easier.
I can't found a single gas giant with panspermia, like HarbingerDawn. Also, for me the system RS 1186-463-5-32511-319 have an oceania with life. But I really found a bug in the panspermia code: meteoroid ejection from desert and oceania was swapped. I fixed it, so now many saved systems with life will be changed This bug may cause the issue with floaters. Did you saw it only with organic floaters?
I think rare panspermia-only systems, even if caused by a bug, are not a big problem, especially since they are theoretically possible. Most systems form in clusters inside collapsing nebulae, and exchange of material between these forming systems is probably not very rare. Even mature systems can send/receive material, but this is much less common.