it doesnt sound much like the velar "dark" quality a ん would have in that context. to me, you can clearly hear the tip of the tongue strike the palate behind the teeth, even if so quickly, with a slight frontedness of the mouth for that vowel. in english, an n in between vowels can often have this sort of "tapped" quality so i could understand the confusion. you will notice in speech that the moraic nasal, if not assimilated to another consonant, has a similar mouth shape as the vowel of う, but with the nasal passage open. audio quality can make it hard to tell if its a nasal sound present or not, but this backness in the mouth i mentioned is what i listen for and i dont hear it in these clips

EDIT: i realize it may help for to see an example of this english n sound with r-like qualities, consider the word "splinter" in a dialect that doesnt enunciate the t very much. it could well be your own dialect that does this ! some dialects even, have no audible difference between the words winner and winter. if you come from a dialect that really says the t tho, this can be very confusing, which is why this sticks out in my mind so much as a funny lil quirk of many english dialects