Sahil, this is the second time in as many days we've seen an issue with an iOS 17 update; the other was the loss of battery percentage with an aftermarket battery. Has the screen on your phone been replaced by yourself or a non-Apple authorized repair center?
I'm not sure we've gotten the full resolution on the other issue yet, but so far the favored suggestion seems to be to try rolling back to the iOS 16.x version you were using before and see if Face ID comes back.