Why am I getting a separate notification for each incoming e-mail?

I recently did a factory reset on my Pixel 6a (running Android 14). Now I find that I get a separate notification in the notification shade for each incoming e-mail. So, for example, if five e-mails have come in since the last time I looked at my phone, I have to swipe away five completely separate notifications. Before I did the factory reset, the behavior I was accustomed to was a single expandable notification that showed *all* new e-mails together. I'd still hear the notification alert sound for each incoming e-mail, but it would then just be added to the existing notification rather than generating a new one. I could either swipe them away individually, or swipe them all away with one gesture. I assume that, at some point, I have changed a setting that governs this behavior, but I can't figure out which setting is relevant. I tried Googling this behavior, but I can't find anything directly on point. What am I missing?