for those who are unaware on the past 24h and since the release of the 9.15 patch there’s a bug exploit that when you sell/remove*rental tanks, *it only notify you for small sales of ammunition and consumables but it will give you for the vehicle’s credit value (unlisted)*as well*. Some players got 8 to 12 Million Credits from this already.

For those on NA, tough luck, its already fixed (came on today’s micropatch), Ghost Prime, a WG NA Community Coordinator gave the following statement:
Dear Tankers,
Thank you for pointing out the issue with the rental system where you could sell the rentals for credits after the 9.15 update.
Good news! This morning’s update has fixed this issue, and selling rental will no longer give credits in return. *For those of you that have sold your rentals for the extra credits, how do you plan to spend them?
Please create a ticket to support if you have any questions or should any issues arise.

However, EU hasn’t micro-patched yet, they will tomorrow (From*06:00 to 06:45 CEST).

Oh Wargaming you done goofed up…