Here is the most recent forum post about replica release e4843a1. I ran into the same issue you described, but the issue was that the script fails the wget command when it tries to download the latest update-img.tar.gz file because the file already exists in my ic folder from the build last week. I deleted the file from my ic directory and then reran the build using the script in the proposal and then both sha256 sums match the payload.
Your verification prerequisites are correct…ubuntu 22.04, wsl2, podman, and git
BTW, if you like to perform these verifications, then you should check out the CodeGov and the Voting Challenge portals on DSCVR. You might find them to have interesting information.