True.
The people who bought before the bundle was updated would need to return to the page to download the updated version.
They will have access to it, but only if they return to the asset page and download the revised version.
This is why following an asset creator can be critical. I have 140+ followers now and those are the set of customers who notice when a significant asset pack update gets posted. Other past buyers tend to miss out. And it's a bit of a shame because some of those updates are quite substantial. One of my texture packs is now almost 3x bigger than when it first launched. Some of my 3d asset packs are like that too.
The followers see the updates in the itch feed. They are actually notified of updates. So that seems to matter a lot.
-Matthew H, matthornb.itch.io