quit making shit up
Here is the faq related to what I am talking about.
https://www.cyberciti.biz/faq/linux-unix-bsd-nginx-413-request-entity-too-large/
Server (application) does not know the site upload limit because it was set by reverse proxy. Any of them could reply with http 413 status and client will just show you the message like screenshot.
It's like leasing warehouses to store all our treasures.
These days pirates do not use islands to bury treasures.