It says under 80%, not idle. If you're over 80% in a 24 hour period, you're likely over-utilizing your VPS.
But why raise tickets though? Since they already measure CPU utilization, it's not hard to also lower priority or throttle CPU or move such VMs to a separate machine where they can't affect anyone but other heavy CPU users.
I'm sorry, that's just dishonest. If you're paying for an allegedly dedicated VPS, or any service for that matter, it's not your i.e. the paying customer's responsibility to limit their use of it within some vague guideline. It's disingenuous to imply a plan comes with X number of CPU cores when it's actually just shared hosting.