I found this out browsing the WT reddit a couple days ago and it just came to my attention to share it with you guys. The Japanese gaming site DMM is holding several promos for WT, you can unlock some exclusive decals and decorations as well. Switch the Language on the launcher (not ingame) and you should get the bonus for all German vehicles.

Here's a link to the reddit post for unlocking the exclusive decals https://www.reddit.com/r/Warthunder/...z_ii_dak_a_3d/