Hmmm, that may happen, but they are actually completely independent. CPP has no information on your DB pension, and your DB pension has no information on your CPP.
What happens is that some (not all) DB pensions have a bridge component, which is approximately the same as the CPP benefit. At age 65, the bridge benefit ends. That's it. You might have been drawing CPP at 60, 65, or not even started. The DB pension doesn't know - or care. If there is a bridge component, it simply ends at 65.