On servers with plugins that constantly churn through scoreboards, there is a risk of degraded GC performance due to the number of scoreboards held on by weak references. Most plugins don't even need the (vanilla) functionality that requires all plugin scoreboards to be tracked by the server. Instead, only track scoreboards when an objective is added with a non-dummy criteria.
This is a breaking change, however the change is a much more sensible default. In case this breaks your workflow you can always force all scoreboards to be tracked with settings.track-plugin-scoreboards in paper.yml.
Andrew Steinborn