Samsung's Galaxy Note 9 is rumored to be coming with an in-display fingerprint sensor according to a report from a couple of days ago. The report, which came from KGI, is now no longer available as it seems to have been pulled from Google Drive where it was initially being stored, but in it the company is said to have asserted that Samsung has chosen to keep the rear-mounted fingerprint sensor for the Galaxy S9 and push the in-display tech back to the Galaxy Note 9 due to Apple's decision to move away from this same in-display implementation on the iPhone 8 series.
Furthermore, KGI also asserts that Samsung will not be using Synaptics technology fingerprint sensors with the Galaxy Note 9 and will instead transition to using fingerprint sensors from Egis, though it was not detailed as to why Samsung would be choosing to make this switch, just that the sensors would be more costly. Rumors of in-display fingerprint sensors have been floating around for a little while and not just for Samsung's high-end Galaxy devices. A leak for the Vivo Xplay 7 from just a few days ago seems to suggest that the phone will come with such a fingerprint sensor design as well, though interestingly enough this will likely be a phone that launches well before the Galaxy Note 9, giving Samsung plenty of time to research the technology a little more before it decides to use the tech itself.
For now the rumors are more or less predictions, so there's no guarantee as to what Samsung is actually planning for the Galaxy Note 9 release, but with rumors already surfacing this early about the phone when the Galaxy Note 8 hasn't even officially been announced, it's likely that more will pop up in the future, and in addition to this it will likely be some time before any concrete evidence shows up that points to the rumors being true or not. If Samsung chooses to move to an in-display fingerprint sensor though, it would probably solve one of the complaints that customers have had about the Galaxy S8 and Galaxy S8+, which is that the rear mounted fingerprint sensor is in a somewhat awkward position sitting right next to the rear camera module, making it easy to brush the camera glass instead and smudge things up.