Token verification failed error occurs

My application is calling v0.5/users/auth/init and getting below request for /v0.5/users/auth/on-init callback url.
{“requestId”:“01c6f642-ca58-4541-a10f-f21d6fc5952f”,“error”:{“code”:2500,“message”:“Token verification failed”},“timestamp”:[2023,12,4,6,31,57,668546000],“resp”:{“requestId”:“4998c5bb-03b5-4aef-9604-19ff2936486c”}}

It was working flow and everything seems to be correct at my end. Could you please let me know why I am getting
“Token verification failed”