Monopolies aren't illegal. Monopolising is illegal, that's the actual word used in the law (3 times in quick succession, you can't miss it), it's a verb, it's an act of doing something. A state of being isn't illegal and in fact you don't need to have a monopoly or even a duopoly or oligopoly in order to fall afoul of antitrust laws.
Part of the problem is that people don't know how the law works, so they look to the wrong solutions, and the media isn't helping. No Google isn't holding an illegal monopoly anywhere that's just Reuters fucked up reporting. Brinkema did not rule Google "holds illegal monopolies" in 2025, that is just again fucked up Reuters reporting.
Those cases rest on actual activities performed by Google and not Google's state of being. The problem really with the USA's antitrust law is the burden of proof that activities actually have an impact on the market affecting customers (in this case ad customers) directly. Most other areas in the world don't have that burden of proof and they can simply apply antitrust law based on economic theory.