> Are you theorizing that the churn causes bugs?

Seems to be the case.

How many times do you see a bug investigation and it's determined when the bug was introduced?

Do you ever look at the diff that introduced it to understand what was going on in the project at the time? Often, it's in service to a new feature. Sometimes the original change is questionable when you consider you traded it for a severe bug.

When more code is written, more bugs are written.

Or, if the act of debugging is removing the bugs from software, then the act of programming is to put the bugs in the software.

Linux is a much larger project receiving changes to tons of systems from lots of different sources. The combined behaviour of those things working together is massively harder to understand and test.

Copyfail being introduced by an optimization made to some random crypto module is a good example of this.

The Linux kernel is generally much larger than OpenBSD which is quite minimal.

But I do agree with you - not directly related to activity.