So i know that there are caps at which you no longer gain bonus xp/tp from housing furniture but...
When you reach max level and no longer gain ANY xp, why is your bonus xp still consumed whenever you kill a mob that would normally grant you xp despite not earning any. I understand why tp would be consumed because you actually are earning it.
It's not a bug, it's a feature.
Seriously though, how quickly do you "earn" that XP bonus back? Overnight, probably. Or a few days, in most cases.
But for the sake of getting 2.5mil tp - 5mil tp depending on how much tp boosting you use, to lose 20mil+ bonus xp for upgrading a skill from 65-68 you are actively punishing players who are utilizing a feature that can cost diamonds (and rewarding a person for not playing at all since they will be better off anyway when they come back for a level cap increase)
IMO, once you've gotten to level 50 or so, you can probably tuck away most of your XP bonus furniture and replace it with TP bonus furniture. Why? Because you can *always* earn TP. And if you haven't capped the amount of XP bonus for a secondary or tertiary class, haul some of the XP furniture out again, and log out on the class(es) that haven't capped yet. It's a little extra work, but it'll balance out eventually.