Just for information. On my server (Linux 3.10.0-1127.8.2.el7.x86_64 + PHP Version 7.3.14) the CRON job should be configured differently.
instead of:
wget -O --max-redirect=10000 /dev/null "http://www.yourdomain.com/index.php?option=com_contentnotifications&task=notifications.createEmailQueue&password=YOUR_PASSWORD"
it should be:
wget --max-redirect=10000 -O /dev/null "http://www.yourdomain.com/index.php?option=com_contentnotifications&task=notifications.createEmailQueue&password=YOUR_PASSWORD"
Maybe it will be useful for other users.