Do people keep their infrastructure as code with their application or in a separate infrastructure repo?

We have created a python library over pulumi and use the library in our application). The library is in our repository . [we are using python3]

Interesting, is this standard practice?

.Net land here. We have projects in the same repo but not opened in the same solution. So same repo but code is separate

We created a library with useful functions / ideas in it and make it available to devs, as a way to wrap up the complexity. Still early stages for us.