Filtration does not reduce duration of poison at all under any circumstances, despite code and config options existing for it
Duration of splash effects and lingering effects, including witch's potions and creeper lingering clouds, is unaffected by any of the stats
Duration of wither applied from wither skeletons and the wither is completely unaffected by withered or detoxification
Duration of poison applied from cave spiders, bees, and pufferfish is unaffected by detoxification
Duration of slowness applied from strays is unaffected by detoxification
Duration of hunger applied from husks is unaffected by detoxification
Duration of mining fatigue from elder guardian is unaffected by detoxification
Duration of darkness from the warden and shriekers is unaffected by detoxification, should probably remain unaffected, as it's a visual effect; possible flashing
Duration of dolphin's grace from dolphins is unaffected by buff purging
Duration of levitation from shulker bullets is unaffected by detoxification
Duration of bad omen from killing pillager captains is unaffected by detoxification, should probably remain unaffected, as it's more of a timer than a status effect
Duration of furnace powered from inner furnace *is affected,* unknown intentional or not
Duration of rumination from herbivore rumen *is affected,* unknown intentional or not
Works as Intended: Wither roses, drinking/eating potions/food, cooldown effects

What this means is buff purging and detox can be mostly bypassed by using splash potions, and withered is almost useless (having one use: wither roses)