Not had a Katz Venom drop at Tshira for around 40-50 hrs grind lately, thats around 100k Tshira mobs and with 100% item collection increase scrolls  turned on all those hrs in solo play,,used to drop at fairly regular spells, albeit slowly, but ive been suck on 65 Venoms for 2 weeks or more. Any issues with these or is it just a brutal run of bad luck for my part? I know its 100k mobs from the Marnis and daily / weekly  quests i do there.

Nope. Maybe 20k max. Only specific mobs have chance for drop, rest you killed for nothing.

Around 7k Tshira mobs each day for over 2 weeks...thats way more than 20k.  As for specific mobs, im well aware that the original single  rare drop was only gotten from the Keepers, but surely the 100 drop Katz Venoms  are dropped by any kind of Tshira mob?..of my 65 ive had them drop on various mobs there and never seen anywhere that says only specific mobs drop those.

100 item treasure parts also drop only from same specific mobs, same as single treasure parts so: Leaf Keeper, Vine Keeper and Grove Keeper.

And that's why this "change" made no sense.

Alright, thank you for clarifying that, i will concentrate on the Keepers then