I'm not sure what you mean by "back in the day" but for as long I can remember, those deals pop-ups have only been shown when I started Steam and opened the mai

I'm not sure what you mean by "back in the day" but for as long I can remember, those deals pop-ups have only been shown when I started Steam and opened the main Steam window. And then it isn't shown again until next time I start Steam, so if I have Steam running for 30 days, I only see it once in those 30 days—when I start Steam. It's never popped up on me while Steam was minimized or even just unfocused. Anyway, if it was as bad as you say, clearly Valve has learned a thing or two and dialed it back, which I think it a net positive. In my mind, using OS notifications to advertise deals is much, much worse because we should be able to trust that our OS notifications are relevant and useful, not that they're ads and spam.