When you select a plan you want to change to from the 'Billing' page -> Switch Plan, different renewal dates are shown for the same plan based on what plan you checked before.
Next renewal on my current plan 'Professional' is shown as 2026-03-11.
If I try to change to 'Starter' plan, it shows me the renewal date same as above: Mar 11, 2026
If I try to change to 'Professional' plan, it shows me the renewal date same as above: Mar 11, 2026
If I try to change to 'Ultimate' plan, it shows me the renewal date: Aug 09, 2025
If I then try to change to 'Professional'' plan, it shows me the renewal date same as above: Aug 09, 2025
Note that I have not changed the plan yet, just looking at what my updated renewal date would be. All other settings are unchanged(Individual/Annual).
I could attach some screenshots if you want but they don't show the name of the plan, so might be useless.
Trying to change to starter plan from Professional plan should have a later renewal date than Mar 11, 2026.
Trying to change to Professional plan from Professional plan should always show the same renewal date irrespective of what pages were viewed earlier by the user.
Edit:
I just changed to Starter plan and I guess my understanding was incorrect. The renewal date is remaining the same but some amount is being added to my balance. My Legacy tag also seems to be lost. It's not showing me the option to change to the same plan I'm on, so it just might be a rare bug that only happens when one is on Legacy Professional and try to change to Professional.