Clarification on 1st Depreciation value and subsequent months depreciation amount on straight line method

Hi folks. We have tried to use the Assets and make depreciation schedule. We are using Straight Line Method over 60 months period with zero residual value at the end of life. Basically if item is $5000 hence the monthly depreciation would be 5000/60 =83.333

However we have observed that the schedule is never fixed. Here the screen

Can anyone let me know why is the system behaving this way. To achieve real straight line method we have to change methodology to manual and insert the depreciation amount manually for each month.

Installed Apps
ERPNext: v11.1.48 (master)
Frappe Framework: v11.1.43 (version-11)