Looks like the little slips of paper to fill out at the airport with your passport and arrival flight details are being done away with. Instead, passengers will have to fill out this form (called "e-arrival"):

https://indianvisaonline.gov.in/earrival/

News articles report this is in effect from October 1.
E.g., https://timesofindia.indiatimes.com/.../124200355.cms

Edit 1: Seems like it can be filled out up to 72 hours in advance. The form does not ask for the incoming flight number.

Edit 2: Different news articles vary in suggesting that OCI holders do or do not need to fill out this form.