project.pj growing in size when checking in deferred (Integrity 10.4)

Recently I stumbled over a project.pj with unusual size regarding member count.

When opening in a text editor I discovered that comments for deferred checkins

where stored there which later on I found plausible remembering information for deferred

operation beeing stored locally.

I then also discovered that on subsequent deferred checkins with different comments

some kind of comment history must be kept in project.pj.

I was somehow surprised though that even checking in undeferred some time later or reverting the

member does not remove that information.

Is there a way to purge project files in a sandbox from such information?

For newer Integrity releases is there a difference regarding handling of deferred operations?