@ShivanikShah: Please try pressing and holding the Side button > Restart, to resolve any temporary software issues. Following the restart, head to Settings > Connections > NFC and contactless payments > On > Contactless payments > Make sure that your default payment option is selected, and 'Pay with currently open app' is toggled on.
If NFC will not remain activated after you switch it on, then please head to the Samsung Members app > Support > Diagnostics > Phone diagnostics > NFC, and follow the on-screen instructions. Do you see an 'Action required' notification in the summary at the end of the test?
