New compilation of 17.1 ISOs?

I just flashed Zorin OS 17.1 Core from the original ISO I downloaded back when it released, but when I checked the checksums, it didn't match. I then realized that if I download the Core version again, as I thought, a new version called r1 downloaded and the checksums matched. Does anyone knows what this new r1 version brings?

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This means that it is an updated ISO. It is still 17.1 but with some newer (System) Packages. But because it has other/newer Packages the Checksum is different.