It all depends on the plastic parts in the fuel system such as fuel lines, floats in the carb, etc. some are only mildly affected by enthanol, while others are slowly corroded, leaving plastic in the solution of gas/ethanol which can clog small jets and dystrophy the lines, etc. I’ve run pure ethanol in racing engines. It has less energy per gallon so larger carb jets are required, but the latent heat of vaporization is higher, cooling the vaporized fuel and producing greater power but with higher fuel consumption. It’s also higher octane than straight gasoline, allowing a higher compression ratio. In the end, it’s worth about a 15% power increase. A downside of ethanol powered race carts is that if the fuel catches fire, its blue flame is very hard to see - just the heat waves rising from the cart.

On principal, I run ethanol free gas (which is easily available where I live) in all my small engines, since some are quite old.