A more practical example is that Facebook cannot promote its marketplace anymore. In Europe there are local alternatives for market places that get disadvantaged.
Spotify, an EU company, has to compete with Apple Music and YouTube Music. Both of which have their own mobile operating systems and markets.
Now we get a lot of backlash from these big tech firms as for years they have been integrating services into their walled gardens. Which now is hard to decouple from their platform.