There are some DeFi projects with impossible yield farming and earnings, this percentage are too high to be true, you can never see such on proof of stake coins yet there are many people investing in such DeFi projects, they won't last long and they will surely exit scam
Maybe this is a little weakness of the Defi system, you have to be extra careful and do thorough research before investing. most projects just copy cat and even just replace their logo without a real use case. look for a project that is really worth investing in