The excuse is more free money. If millions of users rely on the Maps app for recommendations for food places and service centers, why shouldn't Apple exploit their position of power for financial gains?
This argument would have worked except that Apple collects its map data largely from you, the iPhone user, without your knowledge or consent. For example, the live traffic data in Apple and Google maps is incredibly useful, except that they gather this data from aggregated motion and GPS data from users themselves. If you are driving and see through your app that there is traffic ahead, it is because Apple is tapping the phones of the drivers directly in front of you and uploading that data to a central server. So Apple is running their service off of the device you paid for and extracting without your knowledge or informed consent. Now, they plan to place ads into this service as well so that you can pay for the service with your data in two ways.
Beyond this, Apple uses the location data of its hundreds of millions of users to identify paths like sidewalks, parking lots, etc. Essentially, as you walk/drive, you are drawing Apple's maps for them. Apple is taking this data from you for free without any compensation and largely without informing you. So now, it's clear Apple has been building out much of its map data with free labor, and they only send out their little envoy vehicles for data gathering in areas where they do not have enough free labor to do it for them.
The peanuts collab is not an advertisement nor is it a collab. Apple purchased the rights to the Peanuts franchise years ago and they are using the characters as part of their product design. If they are advertising (which they are not), they are not receiving any money for it, and Apple themselves have nothing to capitalize on these "ads" considering there is no product being sold. The Peanuts movie had a weak response and nearly everybody has already watched the Peanuts animated shorts. So no, it is not advertising.