I am unsure if we are on the same page.
You got your Metal card , you did txn and you got Cashback of 4k and waiting for 10k bonus rp , then you lost your card and want to close the card after receiving 10k rp, this is my understanding
My question is have you blocked your card already and raised request for replacement card ?
Just disable offline , pos , atm txn on your card from the IDFC app and use that card for making online spends or whatsoever the offer you want to avail, only if you dont want to get a new Physical card in any form factor (Metal or Plastic) by paying fees.
Lounge Access is anyhow provided by Dreamfolks which can be accessed by generating QR.
I am still evaluating what benefits you get by preclosing your card before completing 1 Year, after getting the 10k bonus RP