Apple is blocking/deleting 3rd party cookies for Safari users in some situations. This hurts advertisers since their targeted (and especially retargeted) ads are less effective. But in particular, it hurts the ad tech providers that act as the middle men between advertisers and publishers – their entire value proposition is based on the ability to track and target consumers across the Internet.
I was quoted in this article on Axios:
This could be a good thing for publishers if it motivates advertisers to buy ad inventory directly, which is far more lucrative to publishers than programmatic. It could also force ad tech providers to pass through more of the revenue to publishers, since they are providing less of the value realized by advertisers.