ETH is wrapped into WETH during a swap on the Uniswap Protocol.
Swaps on the Uniswap Protocol can start and end with ETH. However, during the swap all ETH is wrapped into WETH.
This is because in order for tokens to be swappable on the Uniswap Protocol, they must be an ERC-20 token. However, ETH was built before ERC-20 standard.
This is why WETH was created. WETH is an ERC-20 token and can be used to swap with other ERC-20 tokens on the Uniswap Protocol.
Thus, ETH can be swapped on the Uniswap Protocol but it is wrapped into WETH during the swap.
Note: If you attempt to swap ETH using UniswapX, you will be prompted to wrap your ETH into WETH before you are able to sign the swap.
This is because all native network tokens (ETH, MATIC, etc.) must be wrapped (WETH, WMATIC, etc.) before they can be swapped on UniswapX.