Interesting. I wasn't aware of the controversy around that assertion. The 2021 study doesn't necessarily seem entirely definitive either in my opinion, the total absence of ticks in the stomach contents despite the presence of many other insects seems suspicious, and they only examined 32 possums from a single area. Nonetheless you're right, the other study doesn't seem to have had the best methodology. I'd like to see more information but a search really only turns up those two studies and a bunch of shitty articles on them.