Steam

Likely something was purchased a day or two before the autumn sale. Steam has been doing this for a very long time, but they began automating it a few years back. You used to have to send a ticket for it, but I remember when it spread across reddit and EVERYONE was doing it. I think that Steam figured, "fuck it, lets not have 6 million tickets for the same problem."

The simple things make us customers for life. Hail Gaben!

They probably hold funds in escrow until games are outside the refund window before paying the devs, it would allow them to do this pretty easily.

I imagine they've had enough refund requests for games that went on sale shortly after purchase that it made sense to them to automate it. Still, if it were me I'd be automating the ticket processing rather than the refund itself to at least screw over a, most likely, large portion of the users that didn't notice.

added to your Steam wallet

Does this mean it's just store credit? Even if it isn't I bet this would motivate a lot of people to buy another game with these funds covering part of it, and the supply of games is infinite so Steam isn't out anything.

Probably easier to automate this than processing a bunch of price adjustment support tickets

Very cool to see given all the things going on with the other companies these days.