Seems the that after the Server Maintenance and a Micro Patch on the Russian Server, Low Tier Tanks are now able to play maps destined for High Tier. Some players shared some games in Tier 4 Tanks playing maps like Cliff, Lakeville, Erlenberg and Swamp.
Seems NA Servers after the micro patch were also affected by this. I believe the micro patch is coming out on EU Servers tomorrow, couldn’t yet confirm this. But lets see what we get.