Why ms dynamics crm creates PluginTraceLog instances with createdon = null?

Hello)
Our crm creates instances of PluginTraceLog with creationon = null
As I can see, these are system logs, because all instances with creationon = null have issystemcreated = true Logs created
In our plugins and actions are created normally.
For this reason, a bulk delete operation cannot delete old PluginTraceLog instances because it depends on the creation date
We have a lot of log instances for this reason.
Does anyone know a solution to this problem and what is the reason?