Summary
The upgrade process shows confusing messages about disablig apps while not disablig anything after all.
Detailed description
During the upgrade process, there's a screen saying "These incompatible apps will be disabled".
Example (no idea why it's suddenly German, sorry):

Those listed apps are in fact enabled and don't have a compatible version for the server upgrade target version.
After running the server upgrade, there is another confirmation screen that there were (in this case three) apps that have been disabled:

However, in fact after the upgrade, when checking back in the app store, the apps haven't been disabled after all:

Side note
This dialog has been confusing me for ages, so it also applies for a bunch of versions <19
Summary
The upgrade process shows confusing messages about disablig apps while not disablig anything after all.
Detailed description
During the upgrade process, there's a screen saying "These incompatible apps will be disabled".
Example (no idea why it's suddenly German, sorry):

Those listed apps are in fact enabled and don't have a compatible version for the server upgrade target version.
After running the server upgrade, there is another confirmation screen that there were (in this case three) apps that have been disabled:
However, in fact after the upgrade, when checking back in the app store, the apps haven't been disabled after all:
Side note
This dialog has been confusing me for ages, so it also applies for a bunch of versions <19