When the fuck is this going to stop! Microsoft lost this monopolizing tactic in a court case decades ago. It seems either no one remembers this fact or that Microsoft hopes it's so. Regulators will you please damn-well regulate. In simple English, do your fucking job.
E.g. you shouldn't be able to use product 1 that has 100Y market in A to create any advantage for product 2 in market B if you know user uses competitor in B who's market in B is For example if you have 2B market in OS you should not be allowed to use OS to advertise your own browser to user who uses another browser with under 200M users.
That would also cover Apple exerting power over 50,000 installation apps.
And by "know" here I mean that if you know user is not using your product yet, you must check the condition or not be allowed to use the advantage (e.g. either you should see Chrome ads in Chrome, or Google cant advertise Chrome to Edge users).