Good point, however, despite the name, I don’t think you can legitimately call their “Overseas Citizenship” an actual citizenship in the usual sense. Holders of this status cannot vote, hold public office (or even employment) and cannot be issued an Indian passport. It’s sort of like a special status that allows them to go back to India easily, but with a pretty name.
Agreed. It is a specialized status but is a form of modified citizenship as you note.
https://www.cgisf.gov.in/page/general-information-on-oci-card/