Inconsistent monetary information for Japan via Billing v2 API

Hi,

we have a presence in different Equinix data centers and retrieve billing information via the Billing v2 API. We observed that the information we obtain for the Japan invoice (and that one only) has inconsistent (dare I say wrong?) tax amount values across time:

• For invoices from 2024-02 (oldest I have) until 2024-05 (which is not downloadable anymore due to the 12 month limit but I have a local copy) the Japanese line items behave exactly like all others we can observe, namely: non-zero taxAmount (10% of recurringAmount) and recurringAmount + taxAmount = totalAmount.
• For invoices from 2024-06 until 2024-08 (both in the snapshot I had from a few months ago and the one I just took now) the Japanese line items now still has a non-zero taxAmount (10% of recurringAmount) but totalAmount = recurringAmount. Checking a few entries we saw that the netAmount is the same as in previous entries which makes me assume that the totalAmount does not include any tax amount.
• For invoices from 2024-09 onward the Japanese line items now all have taxAmount = 0 and totalAmount = recurringAmount. This means that we are unable to obtain any tax information from the invoice other than assuming that the 10% applies to all line items. Furthermore, this data is inconsistent with the reality that there is tax to be paid.

Could you explain why the data is so inconsistent, changing multiple times withing a few months?
Could you also explain why the data for invoices since 2024-06 is inconsistent with the reality?

Is there any resource where changes in the API are documented and where I could have learned about these changes?
What can we expect moving forward? Should we expect the data to change again, hopefully to be correct again as it was pre 2024-06?

Thanks
Jonas