I have some USDT and USDC in my portfolio that I'd want to stake in a "De-Fi" dApp without worrying about it in a long time. There are liquidity pools in Uniswap with attractive stake rates, but there's also Compound.Finance with its lending services. Both of these platforms are built on the ETH blockchain, so gas fees would be astronomically high. I've read about some platforms being compatible with Polygon (MATIC), but I'd have yet to see if it's worth the shot (especially in terms of security/reliability).
Today we have seen why all these fiat currencies are not to be invested, and that is one of the reasons why you shouldn't have stablecoins and evidently not stake them as well. I mean 1 usdt worths 1 usd, and usd is terrible if you ask me, if 1 usd is terrible then 1 usdt is terrible too, no matter if you stake it or not.
As long as governments keep on printing money and mismanaging the economy, the value of dollar (and all other fiats) will drop, and because they drop, even when you stake it you are losing the purchasing power. If dollar loses 10% value and you stake 5% back, that is not a profit, that is actually losing money and you should keep it in bitcoin instead.