mapped property values are reverted after applying additional filters

```javascript
import "date"

mapToDay = (tables=<-) => tables
|> map(fn: (r) => ({r with
// We must override _start and _stop in case they've been added by a previous |>range.
_start : today(),
_stop: date.add(d: 1d, to: today()),
originalTime: r._time,
_time: date.add(d: duration(v: string(v: 60 * date.hour(t: r._time) + date.minute(t: r._time)) + "m"), to: today())
}))

meters = from(bucket: "solar")
|> range(start: -1y, stop: 2023-03-27T20:00:00Z)
|> filter(fn: (r) => r["_measurement"] == "meters" and r["fuel"] == "gas")
|> mapToDay()
|> last()

meters |> yield(name: "raw")

meters |> aggregateWindow(every: 30m, fn: max, createEmpty: false) |> yield(name: "max")
```


Start by running the supplied query and comparing the raw and max yields, focusing on the mapToDay transformation before last() and aggregateWindow(). Trace where the mapped properties are changed or discarded after the additional filtering and verify that the transformed values remain consistent in both results.

Written by the indexing model from the issue text.