Earlier quoted context omitted.
There is very little code that a Googler could write that is unrelated to their employer’s business. You’re almost certainly going to need an explicit carve-out, as other Googlers in the thread have pointed out.
There’s a difference between: unrelated to your job, and unrelated to the business as a whole. In some locations, employers can’t claim copyright on works unrelated to your current role.
(Obviously this is not legal advice, talk to your own layers, etc.)