At least with the most recent update, whenever one becomes hydrated (100/100 thirst) they lose any Stamina effects from potions and, I believe, armor (possibly from food effects, too). I think, as well, that effects on Health + Sated are lost.
It seems to me that the attempt to limit stacking bonuses has caused some issues, as the game recalculates when a new effect is applied, but often this causes an inferior effect with only partial overlap to replace a better effect - it doesn’t make much sense to take an Elixir of Freedom if the next time you take a drink you accidentally lose the Stamina buff. Even if this is intended, the potion effect is still displayed in the UI, and it seems cannot be replaced so long as the hydration effect is in play, so the ‘rules’ aren’t being consistently applied; in short, it’s a bug even if the mechanic is as-intended.
As a more subjective aside, it seems good to make stacking buffs less of a thing so that character attributes (and perhaps armor) play more of a role relative to food/potions/alcohol/sated+hydrated, but the current system of removal and recalculation of non-overlapping buff types + the complete removal of certain classes of buffs (alcohol’s old effect comes to mind) is both making the actual net effect confusing and buggy as well as removing some of the fun of trying to get a good meal + good alcohol + good potion + whatever. I’d suggest making additional effects have weaker and weaker effects rather than removing them entirely - for instance, being Sated might cause a smaller effect if you have a greater Potion buff to Health, and Alcohol effects might be added back so long as they are relatively weak compared to potions and food.