I dunno if I'd really call it a spoiler. All it reveals is that there's gonna be a suit change at some point. It doesn't exactly reveal the entire plot. And to me, the biggest hole isn't to do with the teaser but the camera test. As I said, if this second suit exists then it would've taken priority over the first suit because it's his main suit and they'd need to make sure it was well designed, can be used in scenes comfortably, etc. So if this second suit does exist, there's a high chance it would've been available for the camera test. So why would Reeves use the prologue suit to give us our first glimpse of Batman? It just doesn't make sense to me.
Plus, if the leaker saw a second suit then that surely means that footage of it exists and for every other movie like Far From Home, it's been advertised as "oh they get a new suit, ain't that neat?" I even call into question why Reeves wouldn't reveal its existence at FanDome. Especially when he was straight up talking about how Bruce is upgrading the suit as he goes. Surely he'd take that as a segway to reveal at least some concept art. It doesn't reveal anything big, it's as big of a spoiler as Bruce being in year two more than anything.
Either way, I just think there's way too many holes in the second suit theory for it to be true. Still possible, but I'd be surprised if it does exist