I've seen that as well. I used to think it alerted me to an app that didn't update successfully for some reason, but it still shows up on my Pixel 7 Pro, even though all apps are up to date. Oddly, I don't see that warning icon in the Play Store of my Pixel Slate. They're both the same version of the Play Store app.
I also checked the Play Store on my Galaxy A7 lite running Android 13, and it's not there either, so it's not an issue with the Android version. It may just be a Play Store bug on Pixels. Send feedback to Google about it.