Cause of the issue : The schedule report and ad sync is using the same thread pool , so if a report has used the thread and then AD sync runs on the same thread incorrect user is updated in logs.
Workaround : Execute the following update query in the database,
update task_input set pool_id=(select threadpool_id from threadpool where threadpool_name='reports') where task_id in( select task_id from TaskEngine_Task where task_name='ScheduledReportTemplate');
Notes : Please take the backup before running the given query. Also monitor the AD sync for some time .
If the issue recreates need the following query outputs :
select * from task_input where task_id=(select task_id from TaskEngine_Task where task_name='ScheduledReportTemplate');