Initial Person Number is not incrementing in correctly

Summary: We have noticed big gaps in the automatic Initial Person Number increments. We are expecting the sequence to increment by 1 but in some cases the gaps are 3501, 4215, 4559, 7003, 7761, 17037.

So far in August a total of 759 person numbers were generated by the system. On 01-Aug-2024 the last person number generated was 688669 and then on 28-Aug-2024 the last person number generated was 815639. How is that possible that the person number range increased by 126970 while only generating 759 person numbers?

My client is very concerned about this as we want to stay in the 8 digit range for as long as possible but at this rate we are soon gonna go into the 9 digit and 10 digit ranges.