TBH bounties, like airdrops (atleast in the classic BTT sence) are long dead.
Most serious projects don't even hold bounties, and if there's an airdrop, it's done via smart contracts
You are definitely right. The era of free airdrops and free bounty tokens are gone through traditional website and portals. The most profitable now are the smart contract airdrop or AMM drops like uniswap, and those are interacting with some defi projects which give you a valuable drop for a new projects. Mostly Ive noticed are badger dao, yfi, aave, sushiswap and most common defi platforms.