Hi Dweomer!
With the bundle you get all the released asset packs up to the point of purchase. Once you purchase the bundle, it doesn't get updated with future releases.
To keep your collection updated at the lowest price, it's advised to have a Minifantasy Patreon subscription. Alternatively, you can buy the new pack releases directly in Itch.
Here you have a link to a post that explains it all in detail -> https://krishna-palacio.itch.io/minifantasy-dungeon/devlog/701876/how-to-get-the...