(I split this discussion off so that it’s easier to find on its own)
Why wouldn’t it? :P Typst has no way of knowing which execution of the show rule you’re currently interested in, so it shows all.
If I’m interested in something specific, I often create an extra variable for that:
if it.supplement == "Fancy Equation" {
// hovering over this will only show `it` from certain executions
let dbg = it
}