Debian isn't a single person. A lot of patches are backport fixes for CVEs.
Then there's stuff like: "this project only compiles with an obsolete version of gcc" so the alternatives are dropping it or fixing it. Closely related are bugs that only manifest on certain architectures, because the developers only use amd64 and never compile or run it on anything else, so they make incorrect assumptions.
Then there's python that drops standard library modules every release, breaking stuff. So they get packaged separately outside of python.
There's also cherry picking of bugfixes from projects that haven't released yet.
Is there any reason you think debian developers are genetically more prone to making mistakes than anyone else? Considering that debian has an intensive test setup that most projects don't even have.
What gives you the idea I think Debian are any more prone to mistakes than anyone else? It’s one of the two distros I use at home. I admire the devs a great deal.
I mean, it would depend on what the patch is? If you're adding a missing manpage, I'm not sure what can go wrong? Is changing the build options (e.g. enabling or disabling features) a patch, or an expected change (and if such a config option is bad, what blame should be put on upstream for providing it)? What about default config files (which could both make the software more secure or less, such as what cyphers to use with TLS or SSH)?
Then there's stuff like: "this project only compiles with an obsolete version of gcc" so the alternatives are dropping it or fixing it. Closely related are bugs that only manifest on certain architectures, because the developers only use amd64 and never compile or run it on anything else, so they make incorrect assumptions.
Then there's python that drops standard library modules every release, breaking stuff. So they get packaged separately outside of python.
There's also cherry picking of bugfixes from projects that haven't released yet.
Is there any reason you think debian developers are genetically more prone to making mistakes than anyone else? Considering that debian has an intensive test setup that most projects don't even have.