@CanisPundit That rubber thingy is called a splash guard or a disposal splash guard. It helps prevent food particles and water from splashing back out of the garbage disposal unit. If you need a replacement or are looking to purchase one, you can find them at most hardware stores or online.
@Dane thanks. You never know how Alf might answer.
@CanisPundit @Dane I just discovered this recently, but I got there through ordering a “gasket” from Insinkerator that turned out to be an installation part, not a baffle 😭
https://www.lowes.com/pl/appliance-parts-accessories/garbage-disposal-parts-tools/splash-guard/3653102784-4294582389
@Alfred @CanisPundit