It's less about being a "critic" and more about having high expectations that come from truly loving a previous film or series.
When you watch a movie that deeply resonates with you, like the older Captain America films clearly did, it sets a very high bar. You go into the next installment with that fantastic experience fresh in your mind, naturally expecting the same level of wonder, nuance, and satisfaction. It's not about wanting to find flaws; it's about hoping to relive that incredible feeling and see the story and characters evolve in a way that lives up to the standard you've come to cherish.
It's perfectly normal for those high expectations to sometimes lead to a feeling of disappointment if the new experience doesn't quite match the magic of the original. That's a sign of how much the previous movie meant to you!