Berries are neat but yellow berries giving +25 stamina is kinda busted. Its a good idea but due to this they really devalue the other stamina giving items.
Food tollerance really doesn't ballence them even though it should in theory (unless food tollerance gets updated so that some foods can be eaten less than others before kel refuses to eat them)
Alternatively yellow berries could give diminishing amounts of stamina the more theyre eaten in a row, IE the first berry is +25%, the next is 20, 15, 10, and bottoming out at 5. wait a day or smth and itll go back up to +25%. Gives a tradeoff like the other stamina granters (sodas are fairly expensive, coffee makes your camera jitter the more of it you have, coffee bites/bar dont have many uses to them, and others like the alien yogurt are rare)