That cheaper 88 octane fuel is a blend of 85% unleaded gasoline and 15% ethanol. It’s also known as E15 fuel.
The ethanol is an oxygenate: it adds oxygen atoms to the fuel mix so the fuel burns more completely. That’s good for vehicle emissions. However, the ethanol is less energy dense than gasoline so you will get slightly worse mileage.
https://www.motortrend.com/news/what-is-e15-gasoline-pros-cons/
If you want to make a formal feature request for the default Lemmy web interface then you want to go here: https://github.com/LemmyNet/lemmy-ui
I don’t think there is a Lemmy community for informal feature discussion with the developers.
As some others mentioned, the behavior might be different if you are using an app or an alternate web front end.