New cat behavior question

Hi i live in a board and care home that let's me keep my cat she's 9 in September
We have double doors to a patio she can see the birds that eat out there
I feed birds so she has entertainment
She's always been an indoor cat
We have lived here 8 years
The last few weeks she sits and stares out through the crack where
She watches the birds however she does this at 2am now
We are on the 2nd floor so no rodents and the birds show up
During the day not that time of night
My question is what changed her behavior?

Is she fixed? No doubt some creature outside has caught her attention. She can probably hear it.

Yes she is fixed it's just weird she's never done that as long as we have lived here

I don't think it strange really. There may be a possum outside or something like that, which you can't see, but she can hear it.

I agree, I bet that suddenly a new animal is making it's rounds outside at night now.

My mother has two indoor cats.. A few years back, suddenly, a random cat started showing up at the same time, every evening, to one of their windows, just to see one of her cats. At first it was scared interest, then it was growling and hissing, and then after time passed, it was chirping and meowing.
This has been happening for several years now- same time, every night! We jokingly call the visitor "Gussy's girlfriend" (everyone is fixed, by the way).

So I say all of that just to say that it could just be a new animal hanging around.
They can smell them or hear them, even if you're not on the first floor.
It's actually a good thing- switches up her routine a bit and makes it a little more exciting for her!