"$request_headers" and "set_by_lua_block" not working after updating nginx version

Question

nginx: [emerg] unknown directive "set_by_lua_block" in /etc/nginx/conf.d/example.conf

"$request_headers" and "set_by_lua_block" not working after updating nginx version to nginx version: nginx/1.21.6

why "$request_headers" is not working after updating nginx version to nginx/1.21.