You can increase the size with --max-http_header-size the default is 8kb in version 12
--max-http_header-size
Check Out : https://nodejs.org/download/release/v12.18.0/docs/api/cli.html
Run:
pm2 restart all --node-args="--max-http-header-size=65536" (64kb)
pm2 restart all --node-args="--max-http-header-size=65536"