Email notification threshold not respected

I run several sites and this does not occur there. Let's investigate.

Go to /admin/config/development/configuration/single/export, get update.settings and post that here. In the output, replace email addresses with fake ones @example.com.

Ok here is that output:

_core:
default_config_hash: 2QzULf0zovJQx3J06Y9rufzzfi-CY2CTTlEfJJh2Qyw
check:
disabled_extensions: false
interval_days: 1
fetch:
url: 'https://updates.drupal.org/release-history'
max_attempts: 2
timeout: 30
notification:
emails:
- me@mysite.com
threshold: security

That looks fine. Have you been able to reproduce this bug on a newly-installed Drupal site? I think we need to rule out patches, etc, if you haven't already.

It does seem to be isolated to this particular install, still I can't figure why exactly that would be. There are no patches currently applied. Any ideas on what could trigger this malfunction?

Could anything be overriding configurations, in, for example, settings.php or services.yml?

I did find an errant slash in settings.php, just a random keystroke I think, that was inadvertently uncommenting this line:

/ * - \Drupal\sqlite\Driver\Database\sqlite\Connection::__construct()

I've removed the slash and will monitor the behaviour, but I suspect this was the issue. Thank you for suggesting settings.php–I would have never thought to look there.

The last comment suggests that this has been resolved. And presumably the daily email have stopped since there hasn't been a comment in three months.

Just a quick update this has not recurred since the fix.