Instant 4% gain by staking eth in Kraken?

Hello!

I'm looking for options for staking my eth. I was inclined for using Lido (I own a ledger wallet and they seem to work well together). However, I was looking at the staked coins that exchanges use to keep staked eth liquid and saw that in Lido the stETH/ETH is 0.99 while in Kraken I've seen the ETH2.S/ETH as low as 0.96. Does that mean that if I buy ETH2.S in Kraken at that rate I effectively stake my ETH with an instant 4% gain? Why is the value of the staked coin so different across staking services? Do people trust lido that much more than kraken?

I hope these questions are not stupid, I'm new to this. Any help is much appreciated.