@Mark-S at that price the tea is unlikely to be medium quality, more likely low. What you describe sounds to me like the problem is the tea. Not even mentioning that genuine DHP is not available at even close to this price point, so to begin with it’s something else than written on the bag.
I also don’t think boiling a pot with tea is not a very good idea. All the bad stuff is gonna come out and impregnate the clay.
I’d reset it with sodium percarbonate and then slowly season it by brewing. There’s no shortcut to season a pot, patience is key.
If anything, after the last brew, leave the tea and water for a night, before drying it.