A search-style issue usually means discoverability is weaker than expected when someone tries to find an account or its posts. Reply deboosting is different: the account may exist, but replies can be harder to surface in context.
A public checker can inspect some of that evidence, but it cannot reconstruct the full ranking logic used by the platform.
Why this distinction matters
If you collapse every reach problem into the same label, you end up prescribing the same fix to different problems. That wastes time and can hide the real operational issue.