Actually, Caith's patch notes here: https://forums.daybreakgames.com/eq2/index.php?threads/update-notes-tuesday-july-30-2019.590219/ say: You may now disable adventure experience, which includes pvp experience, by right clicking your experience bar in game. so it does appear that something requires fixing.
your feeling is incorrect. you wanted the command and that's how i start looking for them when i don't remember also try /toggle <tab> as i think the command i was thinking of earlier is /toggle_bonus_exp and not /disable_bonus_exp