Covered Call Income ETF's

I can't find an honest answer so please don't flame me! Covered call income ETF's look too good to be true. SPYI, QQQI, JEPI, JEPQ etc. There are hundreds now. I know they generate income by covered calls, but my question is this. They are generating 7%, 8%, 9%+ income along with a reduced upside. Do they generate these returns as strictly income or are they also returning part of your principle in order to maintain these high percentage payouts? Thanks!