I just recently started using Coinbase Wallet (which I will from now on refer to as just Wallet) and connected it to Uniswap to be able to buy some Celsius. I have some various coins on Coinbase (not Wallet), so I sent ~60 USD worth of ETH to my Wallet. Then I went to convert it to Celsius, and it says mining fees are high and my 60 USD worth of ETH won't even cover the mining fees to convert 1 USD of ETH to Celsius...
However, back on Coinbase, I can buy, sell or convert ETH into almost any other crypto for very low fees (I think the fee to buy/sell is ~1 USD, conversion seems free?).
Why is this? Are there no blockchain transactions involved when buying/selling/converting on Coinbase?