Good Morning Siddhant Singh,
I double checked this in my machine
Can you go to:
GL/Setup/Fiscal Calendars
Select the fiscal calendar that is associated with your company (=> please check this in the ledger form in GL)
Create new periods in the fiscal calendar e.g. for 2021, 2022, etc.
Please create some additional years in the future.
Once this is done, try creating the timesheet periods again.
Should work in my opinion.
If you are unsure try to test this in a demo/test environment first.
Best regards,
Ludwig