Like I said it's fearmongering and it's honestly not the first time Unity got a bad reputation. The engine itself nor games made with it won't magically become viruses because of this merge because installcore(the open source installation SDK) is deprecated and IronSource themselves shifted focus from installcore to the mobile app and game market. They are now one of the major players in the mobile development market. In fact nothing major will come from this merge to the engine itself. The area of focus for this merge were mobile ads which are again going to be optional and if you want to use some other company for ads rather than Unity Ads you can and always could do. You can use Ironsource SDK for mobile ads in your Unity game right now as we speak.
You can still use Unity and still make games with Unity and it will still be continued to be used. However I would say switching engine if you are worried about the future of Unity and how the former EA CEO who is now Unity's CEO is running the company worries you then yeah consider switching. To what? I have no idea.... GODOT 4 when it comes out maybe.
As for the reputation hit yeah it's to be expected. Unity has always had a bad rep with gamers in general.
I am not saying the merge is good or any news surrounding Unity is good. 4.4 billion dollars could have been used to I dunno improving the game engine so it stops being such a bloated piece of software. The fact that the company laid off 200 employees who were working on their own game project is really really scummy ,but hey look who's the ceo of Unity now. It's none other than former EA CEO who during his time at the company got an award for the worst company ever twice and who got laid off by the company themselves because he basically destroyed many game studios under EA. The dude called game developers who don't focus on money when developing games f-ing idiots.
If there is a reason to switch it's because a former EA ceo is now the CEO of Unity and he as always is a greedy f-ing idiot.