I am unable to understand the viewpoint of your employer. An employee, after appointment, is placed on probation for a period of 3 months, 6 months, or even one year in some companies.
Understanding the Probation Period
When we refer to a probationer, it means they are not fully equipped or competent enough to deliver results. During the probation period, an employee learns about their job, department, interaction with the Head of Department (HOD) and other department colleagues, the work environment, company policies and programs, HR policies, etc.
Performance Reviews During Probation
Periodical reviews and evaluations of performance are conducted by management on a bi-monthly or tri-monthly basis. Shortfalls in performance are communicated to the employee, and they are mentored to improve their performance.
So, when the performance of a probationer is not up to the mark, you can extend their probation.
Thanks.