I did see a lot of (different) petunia-like photos… from your recollection, were the errant IDs mostly AI/CV selections (with the symbol showing to the right of the ID) or were they more “deliberate” IDs (without the symbol)?
I think I see where you determine this to be a bug. It’s not a problem of the Life List ignoring the community ID, rather it is a problem of it USING the commuintiy ID. An initial wrong ID has that taxa added to the life list, and then a dissenting ID pushes CID to genus and that gets put to life list, and then the weighted “correct” CID gets added as well. It probably accounts for the reason lifelists are so buggy!
My thoughts are that in “contest” situations, such as for CNC and so on, there are other ways to determine “scores” than using lifelists. For individual users, lifelists are a personal thing, and they might be including taxa they have seen outside of iNaturalist, so we don’t want to be messing with their lists if that is the case! there is a set of tools on the list page that allow the list to be re-built, and that may drop those “seen but unobserved” taxa, I’m not sure…
Leaderboards are hugely problematic, in my opinion. I know that in my case, my species count includes a lot of cultivated species from collections that I have been photographing for a number of projects. I certainly wouldn’t hold my 1500 species against the 500 of someone that only observes in the wild. I would make more spider IDs in one month than Cor Vink has total, but that means nothing more than I am more active in iNat, I am certainly not more capable of identifying spiders!
Back to the topic… it might be an idea to change the title to “Life list uses erroneous community IDs - adding taxa that weren’t actually observed”. Note I take out the reference to gaming the system, as I don’t think that is the intent in this case, or others like it. And if it were the case, it is their list to do with as they please!