The release date for One UI 6.1 for these models was announced on the official Samsung Galaxy user community forum
Immediately after the announcement of the new flagships of the Galaxy S24 line, Samsung announced when the latest One UI 6.1 firmware would reach other smartphones, but among the first six models there were not a single Galaxy S21 or Galaxy S22 line. Now the release date for One UI 6.1 has been announced for these ex-flagships.
The moderator of the thread about One UI 6.1 updates on the Samsung corporate forum announced that One UI 6.1 for the Galaxy S21, Galaxy S21 Plus, Galaxy S21 Ultra, Galaxy S22, Galaxy S22 Plus and Galaxy S22 Ultra will be released the second half of 2024, but not earlier than March. That is, we are essentially talking about the second quarter of this year.
As for the Galaxy S23 line, smartphones in the series will receive One UI 6.1 after another security patch is released for the current firmware (One UI 6.0), and its release is scheduled for mid-February.