Can you sell the R400 Event tank?

This is my first successful event tank that i acquire after playing for more than 7 years (not costantly)

I remember events where you need to farm parts and craft the vehicle and then you could sell it after some time like 90 days or something.

Then why the R400 coupon says i can't sell it and no countdown?

https://preview.redd.it/yynqmlwbcw4g1.png?width=439&format=png&auto=webp&s=6d923f25b9c200b133e3ccc8f61154c73c2e37ae