I recently brought an SE2 in for a screen + battery swap, which basically means they'd just give me a new SE2 at a steep discount.

They didn't try to upsell me at all, but I ended up getting an SE3 anyway (I didn't realize there even was a newer SE).

This is nice of them. I think this is because screen replacement was required and them not having SE2 in stock.

They would tell you and you would notice if your phone was replaced - it would have new serial and 2FA apps won't work on a new phone without reregistration.

Most likely it took them a week to get a new battery for replacement shipped.