Sometimes we engineers do a poor job of communicating complexity: we have un-communicated assumptions that we think the listening party shares. Which sometimes lead to this:

"You could prepend the words “it’s just” to anything, it’s not going to change the fact that you sound completely ignorant and will ignore any challenges that your team communicates to you."

I have often found it effective to counter "just-justifications" with the right representation of complexity. E.g.

"Yes, it's just an API change, but it requires 50 new test cases and impacts 120 existing test cases",

OR

"Yes, it's just a library change, but there are 450 sites in our code that use the library and out of those, 50 involve financial calculations"

Almost always, the manager appreciates this because you would have brought to his attention a problem that would otherwise gone under his radar.