-ment suffix reductions

I came across two different videos in which the suffix -ment was being pronounced in a way that the N sound was completely reduced and the T sound was a stop T.

The words were bewilderment and alignment, and both speakers were from the U.S. Having the N sound reduced like that made it really hard to understand those words.

I had never noticed this before. Is this a specific type of accent or is it something more common?

In an unstressed suffix, nasal sounds like /n/ are frequently reduced to nasality on the vowels. Native speakers hear the /n/; non-native speakers don't, because they don't recognize nasality, especially in a reduced unstressed final syllable. – John Lawler