As another commenter mentioned, it's at least a good marketing campaign, causing me to open the app for the first time in months. Or it might be to gather a baseline of how many people react to their notifications, regardless of their contents? (Perhaps to immediately go to the notifications settings to disable them)
Edit: if the notification is sent by an attacker, does the attacker get access to firebase metrics as well? (Guessing they at least contain info about how many people opened the app)
Edit: if the notification is sent by an attacker, does the attacker get access to firebase metrics as well? (Guessing they at least contain info about how many people opened the app)