1) That's not the installCore SDK. That's the IronSource SDK. Different SDK. One is for installCore the other one is for ads. Also these types of deceptive fake playable ads are nothing really new. Many companies used them and still use them to promote their product. They are deceptive as many ads are ,but usually not malicious.
2)Obviously to you know make ads personal many companies usually collect a lot of data of users. I will say this while this is shady IronSource is 100% not the only company doing this stuff. Google, Meta(Facebook),Amazon even Unity themselves do this. There are bound to be a couple of privacy violations. I think the most famous one is the Facebook one. Google themselves got in trouble with COPPA with Youtube. Again while shady it's really nothing new in the world of mobile app/game development or how ads work in general. You would be surprised with how much Google knows about you.
3)Unity developers can use other ad services other than IronSource or Unity ads.... however reminder that no matter what service they use ads are always going to be shady and deceptive. That's just how ads work nowadays.
What this means for Unity is unknown ,but since IronSource is a massive player in mobile app/games development and one of the massive ad service providers it means Unity will probably use IronSource for their ads. Again this does not mean that every single unity game will suddenly become infested with these ads as Unity ads are an optional package that developers choose to use(unless that changes somehow) and like I mentioned before they can use other ad services. In fact IronSource was one of many ad services Unity developers could and still can use to this day. Some unity developers already use IronSource. Do what you wish with that information.