If this is true, that’s pretty funny. Quite fitting of Nexon to make one of the worst nations even worse. It’s not like the TC defence damage was already negligible after Medieval or whenever. No need to say “rebalance” — it’s more like an unbalancing.
When update 6.6. went out it had the re-balance patch 4 modifications not included. Shortly the patch 4 was implemented again in the background. You might have checked your TC stats after the update 6.6 when indeed the hp was halved compared to the values before the update.