Are swifts flying around my window trying to "scare me"?

I recently moved to a previously inhabited house. I have a window in the first floor. Sometimes, when I open it and lean outside on it, a pack of 4 swifts come and start to fly "aggresively", passing rapidly around my window, doing their characteristic high-pitch sound. It’s a bit scary. They pass very close by, less than two meters away.

I read that

On fine summer evenings Swifts gather in “low flying screaming parties” as birds chase each other excitedly around the buildings where there are nests in high speed, aerobatic groups.

So, there is probably a nest around (something I haven’t really explored). But the question is, are they traying to "scare me" or "warn me" about it? Is there scientific theories trying to explain this behaviour?