When the data in spec changes, the view does not update.

[Sparkier]

If the data that is embedded into spec changes (not any of the keys in data), the view does not update.

[domoritz]

What was the resolution here?

[Sparkier]

I had another issue which made me think this was the case, but I think it is not as I thought.
This is the check if those spec fields are equal (including the data):

    fieldNames.some(
      (field) =>
        !(field in newSpec) ||
        !(field in oldSpec) ||
        !equal(
          newSpec[field as keyof typeof newSpec],
          oldSpec[field as keyof typeof oldSpec]
        )
    )

[Sparkier]

I think my problem was specifically related to the way I feed arrow data to svelte-vega.