Looking at Compound since it's DeFi [1] the rate is 2.6%

CeFi platforms like Celsius or BlockFi can offer more, but they are just as risky as any unregulated sub-prime lender in a third-world country (eg micro-lending institutions can offer those sorts of yields too).

The reason DeFi loans are much lower yield than CeFi loans is precisely because the risk is on-chain in the former case, so deposits can't be stolen.

Not sure where you see 20-30% on USD? Those rates are an indication of a rug-pull scam or a ponzi imho.

[1] https://compound.finance/markets/USDC