Uniswap foundation has been in the swap business for years. Most of the swaps and the exchanges make use of the uniswap in backend for the swaps and the exchanges for their assets. Now Uniswap has decided to build their own chain to reduce the fees and also the load of the on chain assets while the uniswap can reduce on the external interoperable dependency for slippage fees. 

Now that they have created the Unichain few months back, some of the projects are starting to build using the building kit. And the thing about the new chain that is designed for the DeFi and also the fees would be less and also the execution would be lot instant. 

This new chain is based on the Superchain. You may notice that the OP's buildkit being shown by the Unichain and the fees are low due to the Optimism's stack being posted there. I feel this progress done by the UNI is a good direction. I thought from this point onwards the Unichain is going to power many protocols and the swap and exchanges lately. 

You can check out Unichain here.