There's a term for this that I can't figure out how to search for. It refers to the way people don't notice how the natural environment changes around them because it's so gradual. The context I saw it in was, I think, the way someone didn't think much of the lack of fish in a body of water other than having nostalgia for fishing with their dad as a kid.

I think the culprit in this case was overfishing, but the term was general enough to apply to any change like this. Maybe someone reading this knows the term.