This probably have an amazing background story.
AppLovin and Unity has a similar market cap, making this merger almost equal in power - which typically leads to an uphill battle in management of who has the power.
This first and foremost blocks the IronSource merger, and it's probably something that Unity management don't want to do. But the board must consider it or otherwise it will suffer hell of litigation from shareholders.
It's super interesting to see where this all leads.