[MNT] Local pytest failures despite CI passing on main

[jgyasu]

While following the testing-your-installation guide, running pytest locally results in multiple test failures. These failures appear even though the CI workflows are green and the latest merged PRs (e.g. #1502) pass all checks.

This suggests a mismatch between local test execution and CI behavior, or that some tests are not being enforced strictly. It might be useful to treat this as an umbrella issue to identify failing tests locally, understand why they differ from CI, and ensure consistent behavior across environments.