https://wccftech.com/galaxy-note-9-and-galaxy-s9-may-not-receive-the-one-ui-2-1/

Samsung recently started rolling out the update for the Galaxy S10 and Note 10 series that brings One UI 2.1 along with the latest security update. This was not a surprise as Samsung had already announced their plans to bring these updates onto the older devices. However, in the announcement, we also heard that Samsung will be bringing out the update on the older devices such as Galaxy S9 and Note 9 devices, something that made a lot of the older users happy.

However, it seems that based on a new report, the update might not be coming to the older devices at all.