The Ad-Free feature - no volume discount for 3 months option ?

Dear Forum,
This morning I discovered the "gift (member name here) ad-free" feature on some signatures.
I wanted to make use of it for a specific member, so I clicked on it and saw the drop down menu for 1 month, 3 and 12 months.

Doing a quick calculation, I think that the 3 month option has a volume discount error...
Here's why :

Price 1 month : 3.49$ -> 3 x 3.49$ = 10.47$
Price 3 months : 10.99$ -> I believe that this option should be below 10.47$ (see above)
Price 12 months : 29.99$ -> Volume discount ok here.

Can you please check this ?

Best regards,
Ken

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