PayPal Standard code ignores payment amounts in IPN, seems to use original recurring payment amount, doesn't see changes in amount
I suspect this is the same as CRM-21609 (PayPal Pro IPN code no longer respects changed recurring amount) but for standard.
If a recurring payment is increased or decreased from the PayPal side (I think the only way to do with Standard), the IPN shows the correct amount but civi records original amount from when the recurring payment was originally set up.
What I think should happen is, first, it should use the amount in the IPN. After all that is what PayPal charged the person. Second it should update the recurring payment record in recur table with the new amount.
Right now there is now way to change this. One has to go in to each recurring payment each month and edit it to the correct amount. It appears to allow you to edit it and change the amount of the recurring payment but on saving it, it doesn't do anything. I think this maybe part of another bug out there.