The company can stipulate the service period for the unified training fee for employees, but it should also be within a reasonable range! The company has the obligation to pay social security for you from the day you start working (excluding housing provident fund, which belongs to welfare). Because you don't know the cost of your training, it is difficult to determine whether such a regulation is reasonable.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.