For White no spends requirement but for Royale, Mojo, Zen, it was initially complimentary then became spend-based:
https://images.kotak.com/bank/mailers/2023/files/Lounge MITC 12-5 Revised.pdf
"Life time free cardholders need to spend a minimum of Rs. 60,000 on the primary card (EMI spends will not be considered) in a calendar quarter to be eligible to avail the 2 complimentary domestic lounge access for the next succeeding quarter. For example, if a customer wants to access lounges in the 3rd calendar quarter (July, Aug, Sept), his/her spends should be minimum of Rs. 60,000 on the primary card for the period between 1 st April, 2023 -30th June, 2023 ."
I also got an SMS about it.