ivory folio
My suggestion is to make the firefly a medium tank.
Make the tank cheaper, remove the heavy armor it has but don't make it the same price as the Cromwell. Keep the gun as is to give it a net benefit over the Cromwell as a tank destroyer.
REPLACE the firefly heavy slot with the Churchill A22 as a HEAVY infantry support tank. It would work similar to the Jumbo 75 in terms of gameplay but should have more armor/health pool to counteract the current "two shot" meta in game.
The goal of this suggestion is to push us away from the overly simple tank gameplay and expand more into an asymetric but balanced gameplay loop. The idea of having a heavy tank designed for helping infantry and not focusing on fighting other tanks but still being able to deal damage is ideal. You could even make it so the Churchill cannot be damaged from the front as a whole, the same could be done for the 75 jumbo. The tank can't fight the other heavies from the front but it won't be made useless by it's armor being pointless as well.
pseudo ginkgo
calm flint
muted wasp
quiet oyster