It's a common pattern at several of the big software companies to bundle a lot of freemium stuff with their paid core products that then ends up squeezing independent providers of similar stuff.
I love Github. Before MS bought it I was a CTO at a company where we happily paid for it. Now MS offers it for free. I don't currently pay them anything. We also use Github actions. We don't pay for that either. You get 2000 free build minutes per month. So no need. That's great for us of course. But it's horrible for independent providers of CI services, which I used in the past. How can you compete when big companies like MS just pretend build minutes and hosting the world's software projects costs 0$?
I say pretend here because of course in reality MS spends a lot of money on all that infrastructure needed to do that. But they make their money elsewhere. This is just an anti competitive move to ensure enough customers end up paying them. It's a lock in mechanism. But it's also an anti competitive move. It ensures competitors don't stand a chance. Because how do you compete with free?
Of course the flip side is that a lot of things in software become commodities where the price of something goes to zero quickly after the open source world starts providing free and open source alternatives. Zoom is a great example of a commodity with little intrinsic software value. There's very little in there that you can't replicate with free and OSS components. Most of the real cost relates to infrastructure and networking.
Which of course like Github isn't actually free. So MS is subsidizing the cost of having massive amounts of companies run all their meetings on Teams with money they squeeze out of them elsewhere via unrelated products. That's what the EU called out as anti competitive. Microsoft spends many millions/billions on ensuring people get locked into their free offerings just so they can continue to be valued at trillions because of all the revenue they get from us elsewhere. This is not charity. That's how they became this big.
IMHO Gitlab would have strong case too. They are a European company actually (Dutch originally). So this is a clear cut case of a local competitor being squeezed out of the market by MS spending large amounts of money ensuring there is no market.