IANAL, but it means the commit itself is public domain. When integrated into a code base with a more restrictive license, you can still use that isolated snippet in whatever way you want.
More interesting question is whether one could remove the GPL restrictions on public code by telling AI to rewrite the code from scratch, providing only the behavior of the code.
This could be accomplished by making AI generate a comprehensive test suite first, and then let it write the code of the app seeing only the test suite.
