I have updated my iPad Pro 11-inch, 3rd Generation (Model: MHW53HN/A) to iPadOS 16.3.1 and still unable to access 5G services on either Airtel or Jio. Raised a complaint to Airtel technical team, who are clueless and asked me to contact Apple service center. Seems like both Apple and Airtel currently, don't have a solution to this problem.