I saw 1.8.5 is verified, but others are not. Does that mean not recommended to used versions after 1.8.5 for real production? (But there are bugs in 1.8.5 too : / )
Thank you.
Not necessarily. If the package is not in preview it is ok to use I think but there is a higher chance of bugs than verified.
I have been in situations where verified have bugs and had to move to next unverified version. You can always go back. Software will always have bugs! 
Preview < Production <Production Verified
see here:Unity - Manual: Concepts
The package has undergone rigorous testing and has been verified to work safely with this specific version of Unity, and all other packages verified for the same version. This state is only for packages that Unity develops internally. Contact third-party package developers to ask about their specific processes.
When a package is verified for a version of Unity, Unity guarantees to support that verified package for the duration of that version of Unity, throughout the period of long-term support, and does not allow any major or minor updates (that is, changes that break or change an API). With each new version of Unity, each verified package must go through the verification process again before the Package Manager considers it verified.
To see a list of packages that are verified for this version of Unity, see Verified packages
.
Note: Some packages are neither verified nor preview packages. In many cases, this is because a package was verified in a previous version of Unity but has not completed the verification process yet for the current version. For a few packages, they were published to the Unity Package Manager registry because they were considered safe to use, but were never verified. In both of these cases, these packages are safe to use in production.
Thank you !