Eth staking provider. Revolut vs Zengo wallet

I am staking ETH for a long time using Zengo wallet. I always thought they have one of the highest staking rewards when you don't want to stake directly on chain or any other more complicated solution. But recently I tested Revolut ETH staking and results suprised me.

I left the amounts staked on both platforms untouched for 28 days. Then I look at how much did I make by staking on both platforms, devided by 28, multiplied by 365 devided by the amount staked and I got
Zengo: 2.46% ROI
Revolut: 4.92% ROI

That is a huge difference! I wasn't able to find a good source of information on the comparation of different staking providers. All the information and data just provide vague values that cannot be compared.

Was my statistic samle just too small and doesn't actually show correct numbers or does Revolut staking really make 2 times bigger returns? What is the word on the street?

Just to save some time. I know that Zengo and Revolut staking is different. I don't care about that right now, only focusing on pure invest > stake > earn.

PS: I find it ridiculous (borderline illegal) that basically a financial institution (Zengo) offeres a service that makes it almost impossible to check what are the returns. The on chain data are completely obfuscated through their staking provider so there is no way how to see the periodic earnings. Only the overall sum of all your ernings is visible. Apart from making screenshots and calculating it yourself, you have no way to check how much you are actually earning over time.