But that include had never before given problems:

error_page 400 =400 /400.html;
error_page 401 =401 /401.html;
error_page 403 =403 /403.html;
error_page 404 =404 /404.html;
error_page 405 =405 /405.html;
error_page 429 =429 /429.html;
error_page 502 =502 /502.html;
error_page 503 =503 /503.html;

location ~ /(400|401|403|404|405|429|502|503)\.html {
  root /var/www/errors;
  internal;
}

Why are you setting response code to the same you're catching via error_page?

It's a recommendation in an article which I had been using for some years without problems.

Meh...

да

I just removed the =status part, and the problem persists.

Well... You've started with really simple configuration, which should work - and proved to be working.
They eventually some includes appeared. Next findings, I suppose, will be like log_not_found on on a server level.

Could you try this instead, please?

server {
  listen 44480 default_server;

  error_page 404 /404.html;

  location = /404.html {
    root /var/www/error;
    internal;
  }

  location / {
    access_log /var/log/nginx/catchall.log;
    return 404;
  }
}

(Forgive me, I made two editions in orden to make it resemble more my config)

No, I said that if I moved the access_log directive to the location block, the virtualhost was skipped. It works just fine outside, at the server level.

# curl -sk -D - http://127.0.0.1:44480/
HTTP/1.1 404 Not Found
...

# curl -sk -D - -H "Host: lala" http://127.0.0.1:44480/
HTTP/1.1 200 OK
...
OK

# tail *log
==> default-access.log <==
127.0.0.1 - - [07/Apr/2021:17:07:50 +0200] "GET / HTTP/1.1" 404 169 "-" "curl/7.52.1"

==> vhost-access.log <==
127.0.0.1 - - [07/Apr/2021:17:07:59 +0200] "GET / HTTP/1.1" 200 2 "-" "curl/7.52.1"

Works as expected

What version of Nginx are you using?

I guess we need from hugo thus

This

nginx -T

To pastebin

1.14.1 , 1.16.1, 1.18.0, 1.19.9

And we need his curl request

I am using just my browser

, could be a problem, lol

no kidding, LOL