If they show a clearly marked ad in the listings when I type, say, "Italian restaurant" - where it's clear I'm looking for recommendations - then I don't have much of a problem with that. I'm also almost never looking for recommendations in the Maps app.
But if I type "zoo" and it says "wouldn't you like to go to Sea World™ instead?" - or I type "Lowe's" and it says "wouldn't you rather go to Home Depot?" - then I'm going to be really annoyed, because it's actively hampering my use of the app for someone else's benefit, making me the product. I'm also going to be really annoyed if the maps display starts getting littered with "7/11™" and "Arby's™", because companies have paid to be highlighted on the map, because then it's making the display just plain worse, to rake in that sweet ad money.
I thought that the exchange was always, "we pay Big Money up front for Apple devices in exchange for a premium experience, where we are the customer". Not us being the product sold to third-party advertisers - that's Google's domain, and one I've gone out of my way to avoid.
I actually used Google's Maps app yesterday, because Apple wasn't able to provide directions (at least in Southern California) for a while yesterday afternoon. I'd rather use Apple's maps - the display is better - but it seems like Apple is looking to lessen the experience.
At the minimum, they could say, "ad-free Maps+ are a $1/mo subscription now, but we'll waive the cost if you're subscribed to any of our other services, like Apple One, Apple Music, Apple TV, iCloud+, etc.". I don't imagine they're going to be making more than $1/mo/person off these ads anyway, and it would nudge at least a few customers to subscribe to that thing they were considering anyway because this "sweetens the pot".