In the last patch many people lost out because most stacks of 200 in guild banks randomly got cut down to 183. I was told that the fault will be addressed with the maintenance that just took place last night.
This morning I find that almost all my stacks increased to over 200. Some to 217, some to 230, some to 250! I didn't keep an accurate inventory of my guildbank, but I don't think my items were somehow restacked, so it appears I've just got a bunch of free alchemy flowers and other relatively cheap materials, which is still a significant sum of value for most people. However, I would be shocked if more greedy people didn't try to get freebies by placing stacks of valuable items like Tempering Alloy and Kuta into their GB last night, and judging by the evidence of my guildbank, they just got a lot of very valuable freebies.
Please look into this zenimax. Yes I benefited from whatever you did last night, but this is not right and it destroys my confidence in the guild bank system as a whole. I shouldn't have to keep accurate excels spread sheet accounts of my guild bank to make sure I don't gain or lose stuff randomly.