The update process works just fine
Get:2 https://artifacts.elastic.co/packages/8.x/apt stable/main amd64 elasticsearch amd64 8.16.0 [635 MB]
Get:1 https://dl.packager.io/srv/deb/zammad/zammad/stable/debian 12/main amd64 zammad amd64 6.4.0-1731532686.9edee425.bookworm [177 MB]
Fetched 812 MB in 9s (95.0 MB/s)
Also the packages build just fine, there is no error. pnpm is available in the build, it clearly states.
Looks like it’s a local problem on your end.