I've noticed that during festivals 1. I run out of space in my inventory lol and 2. when my inventory is full and I get sent items that I won but don't get immediately because my inventory is full. It's pretty annoying to fight someone (especially named) and get sent each and every item individually. I want to keep the items, but things such as event currency get sent one by one and clog up my inventory so fast. Maybe I'm just jaded because this happens multiple times during every fest, but I also don't want to buy new inventory tabs all the time.

I agree...
I think for this past winter fest, I was busy battling and didn't realize that my inventory was full (I have three tabs which is usually enough) and I had to spend at least half an hour going through 3 pages of frost tokens in the trades...

It's especially annoying if I know everything will fit if they were stacked with pre-existing stacks but when I need to take them from the trades, I first need to make room in my inventory, accept however many trades as I can, then stack all the items, and repeat (repeatedly).

I guess possible solutions would either be to have dropped items that you already have in your inventory (like tokens) to automatically go into a stack in your inventory, or to have then stacked in the trades so that you only need to accept one trade to get 20 tokens instead of 20 trades...