ETH – rETH exchange rate in the Rocketpool beta

I tried the rocketpool beta on the goerli testnet (over at https://beta.rocketpool.net/) and exchanged some goerli eth I got from a faucet for rETH.

From my understanding, the ETH is deposited into a pool from which the required stakes are drawn and to which the staking rewards are sent. By depositing some ETH into it, I get rETH, which represents my total share of the pool. In the beginning, the ratio should be 1:1 (this is also shown in the latest medium article https://medium.com/rocket-pool/rocket-pool-3-0-beta-finale-fb35c4f8e003)

As the staking rewards come in, they are added to the pool. This of course means that my rETH I got earlier are now worth more (same share of a larger amount = more worth, at least once I can withdraw). This also means that I will get less rETH when I deposit ETH. (For example, if 1000 ETH were deposited initially for 1000 rETH, 1 rETH represents 1 ETH in the pool. Now 100 ETH of staking rewards are added, and 1 rETH still equals 1/1000 of the pool, meaning it represents 1.1 ETH in the pool. If I want to buy a share now I have to deposit 1.1 ETH because that is the current ratio)

But this shouldn't be noticeable in the beginning, should it? The beta started today, so basically no staking rewards could have come in. But the beta shows me a ratio of 1 ETH for 0.78 rETH: https://imgur.com/a/kwdNx6Q

Does anyone know what's going on?