Some players noticed due to Stalingrad Full access pack force sub-top level soldiers/weapons. So you can sell most soldiers/weapons for more bronze. Actually a way to transfer silver to more bronze.
Though, I have tons of weapons in other campaign, so I simply transfer them to this campaign.
Also. No need for tickets to me.

Think twice before you buy anything in Stalingrad. ESPECIALLY SOLDIERS! You will run out of reserve and no way to remove one.
it is an error, xeofox already mentioned it and says that they are already solving it
They realized the “discount” upgrade price with full sell back value was clearly being exploited
Its a temporary fix while they are rethinking the prices/returns