I recently bought a Revell maquette and got 3 invite codes and a bonus code inside, so I’m sharing them here for new players to enjoy a little boost.
Bonus code: RMKR-B7G3U-AENM8
It contains in-game mission that, upon completion rewards you with:
2x +50% experience for 2 hours
2x +50% credits for 2 hours
2x +50% crew experience for 2 hours

Invite codes:
1. RVER-AMZD8-4NV2H
2. RVEG-X7C77-9XGCU
3. RVEW-R9VY6-N68EK
These contain:
T2 Light Tank
Garage slot
7 Premium days
1000 gold
To claim the invite codes you need to go to this website. Note that the codes work for EU server only and are valid until 31. December 2023.