Issue #3248544: Build in some buffer time when validating cron frequency based on last run time

src/Validator/CronFrequencyValidator.php

@@ -171,12 +171,9 @@ class CronFrequencyValidator implements EventSubscriberInterface {
     // installed, defaulting to the beginning of the Unix epoch.
     $cron_last = $this->state->get('system.cron_last', $this->state->get('install_time', 0));
 
-    // @todo Should we allow a little extra time in case the server job takes
-    //   longer than expected? Otherwise a server setup with a 3-hour cron job
-    //   will always give this warning. Maybe this isn't necessary because the
-    //   last cron run time is recorded after cron runs. Address this in
-    //   https://www.drupal.org/project/automatic_updates/issues/3248544.
-    if ($this->time->getRequestTime() - $cron_last > static::WARNING_INTERVAL) {
+    // Allowing a little extra time (120 seconds) in case the server job takes
+    // longer than expected.
+    if ($this->time->getRequestTime() - $cron_last > (static::WARNING_INTERVAL + 120)) {
       $event->addError([
         $this->t('Cron has not run recently. For more information, see the online handbook entry for <a href=":cron-handbook">configuring cron jobs</a> to run at least every @frequency hours.', [
           ':cron-handbook' => 'https://www.drupal.org/cron',

[Ted Bowman]

I don't think this gives enough information as to why we need this buffer. I feel like if saw this later I would probably do a git history to find the issue that added this change. And someone not involved in this issue would have no other context.

I am going to push up a suggested change for others to review.