Oh, and to add to the interest: one of the earlier issuers of such 'buffer funds' is FirstTrust/Vest.
VEST is actually a marketing arm of CBOE to commercialize some of the various "mechanical option strategies" for which CBOE publishes backtests (they call these backtests 'indices")
https://www.cboe.com/us/indices/indicesproducts/

Ever want to know how a well-specified "butterfly" options strategy did back to 1993 (or whenever it was)?
A published backtest, by a trusted source, of a mechanical option strategy is in fact sort of nice, it scratches the itch.

But the backstory is that CBOE makes money via VEST by licensing (I assume it's licensing, I don't know that) a CBOE strategy to another firm like FirstTrust, who then bundles it into an ETF and sells it to you (with presumably some percentage back to CBOE, because altruism tends to get arb-ed out in finance). All the funds that I've looked at use FLEX options. FLEX options are bespoke options that are issued by CBOE after a firm like FirstTrust negotiates with them.

I'm not suggesting that these funds are bad things, but when things get fairly complicated it's good to get extremely careful.