In my opinion, the biggest (and quite possibly most dangerous) problem is someone artificially pumping up their ideas. To all the users who sort by active / hot, this would be quite problematic.
I’d love to actually see some social media research groups actually consider how to detect and potentially eliminate this issue on Lemmy, considering Lemmy is quite new and is malleable at this point (compared to other social media). For example, if they think metric X may be a good idea to include in all metadata to increase chances of detection, then it may be possible to include this in the source code of posts / comments / activities.
I know a few professors and researchers who do research on social media and associated technologies, I’ll go talk to them when they come to their office on Monday.