I've seen some things. Binaries, large files, isos, generally just any large file with no lines that somebody just didn't know better and committed, changed a few bytes a few times, and generated huge deltas quickly.
I'm far more surprised you don't know what he was expecting than I am that he asked, considering how many times I've run into this in the past.
https://github.com/oracle/graal
It's not even a mono-repo - this is just part of the project.
Maybe someone's got some tools that let them dig around in the history and find large things or explain why it's so large? I don't think they've been checking ISOs in.
Receiving objects: 100% (981372/981372), 187.08 MiB | 6.39 MiB/s, done.
% du -sh graal 328M graal
% du -sh .git 221M .git
And that includes many binary files that were added and removed over time, but not filter-branched out of existence, including jars, pngs, pdfs :)
(https://stackoverflow.com/questions/10622179/how-to-find-ide...)
The biggest issue is actually the l10n stuff. It’s all text with lines but there is a lot of it and historically the exports were not really ordered so every major update to the translation files scrambled everything.