Google says:
A 413 Request Entity Too Large error occurs when a request made from a client is too large to be processed by the web server. If your web server is setting a particular HTTP request size limit, clients may come across a 413 Request Entity Too Large response.
Means, the HTTP request payload being sent to the lambda server in your case gets so bigger that it is being rejected by it.
@gja have we set a request size limit on the Slash lambda servers? Any ideas how to tackle this?
Should we make requests in multiple batches of limited size or the limit can be increased?