So, this is the DCEU's Batgirl costume.

Did they run out of money

My guess is that it's supposed to look home made

Why are the boots brown

Because they were in the comics.

It's based on the Batgirl of Burnside outfit.

meanwhile, over at Marvel...

I like it

It's also going to be HBO Max versus full theater release, and since it's based off the Burnside outfit, it makes sense overall. I hope they at least give her an upgrade midway or at the end.

That's the rumor, her getting an upgrade from Keaton!Batman.

The cowl looks good though, and I think that's the big sign that we're supposed to take the costume's appearance as being an in-universe thing versus budget thing, if that makes sense.

It does.