413 Request Entity Too Large nginx/1.18.0 (Ubuntu)

Problem Solved

In addition to increasing the maximum size in nginx.conf, php.ini and wp-conf.php files, it was necessary to raise the limit in the nginx server block for the site. I increased the default value of

client_max_body_size 2M;     to
client_max_body_size 200M;

and now all uploads go smoothly and quickly.

Hopefully, someone can tell me why I had to modify 4 separate files in order to raise the size limit when uploading files.