Why? Because Google recently stepped up its notification spam in their official apps. They're using a mechanism that's supposed to exist to notify me of things _I_ want/need to know about urgently instead to advertise products and services to me that I have no interest in.
It's tedious to track down all the places these are coming from and disable them. And I shouldn't have to. I paid a premium for a high-end flagship Google phone. As a phone user, I have to give the vendor power to do all kinds of things on my behalf and to me — in this case, the power to pull my focus, or even wake me up in the middle of the night. As a phone user, my bare minimum expectation is that this power will be respected. And yet Google has chosen to use this focus-pulling notification mechanism to serve me ads.
Google does not respect even their paying users. It feels like somewhere deep in their corporate culture, their users barely even exist to them. I'm just a sub-pixel blip on a request rate dashboard, and if they can temporarily increase my "engagement" by slapping me in the face, then a slap in the face it is.