Is swallowing phlegm and mucus or inserting a finger into the ear among the things that invalidate the fast?

Swallowing phlegm does not invalidate the fast, even if it reaches the mouth and the fasting person swallows it. The fundamental principle is that the fast is not invalidated when in doubt, and this is not akin to eating or drinking. As for inserting a finger into the ear, or placing drops or medicine in it, this does not invalidate the fast, even if one tastes it in the throat, because there is no evidence to suggest that it invalidates the fast.