Good question. Rewards vary because: “Ethereum staking APR is mainly affected by the number of active validators that dilute staking rewards and by the network activity paying out more or less transaction fees, priority tips, and through MEV opportunities created.“ That quote is from this site: https://www.kiln.fi/post/pos-ethereum-staking-rewards-a-deep...

But, if I were to assume a rate of 4%, compounding monthly, for 20 years. 32 could turn into 71. I got that number using this calculator:

https://www.mathportal.org/calculators/financial-calculators...

That’s not considering gas fees for the compounding transactions though. Nor the cost of running the server. But I guess it’s a rough guess.