I think amazon : amazon basics is a great example of antitrust/unfair monopoly the same as google search : almost all consumer facing google products.
Both amazon and google search are the dominate online market leaders in their respective categories. In amazons case they unfairly use their market position to begin offering amazon private label products on their platform. They know what users are looking for, spend the most on, and they can give their own products dominate positions in the UI. In the case of google they too unfairly use their position as a market leader against their own customers (advertisers), so say you are a hotel booking platform and spend $x with google, google knows the market (searches, clicks, etc...) so google launches their own hotel booking, gives their in-house service priority in search results over existing market incumbents and self bids on google search advertising for key industry terms to drive up costs of advertisers to keep in business.
It’s kind of like standard oil buying up the railroads so they owned the supply chain and no other oil could be moved. It’s unfairly using your market position, not to compete, but to be anti competitive to the detriment of consumers.
I’d like to see the tech giants prevented from unfairly using their market dominance to stifle competition. As we saw with the break up of standard oil...competition is good for consumers.