i just discovered this after 2 hours of testing
If you define error_page for a server block multiple times, only
the first one will take, subsequent ones will not override
That means if you store your error pages in a macro, to override it
error_page 503 /503.error include /usr/local/nginx/_macros/error_page.conf;
include /usr/local/nginx/_macros/error_page.conf; error_page 503 /503.error
I’m not sure if this was intended or not ( personally , i don’t like
but I wanted to share this with others.