Guild Upgrades is VERY unstable when it comes for prerequisites!

Example:https://api.guildwars2.com/v2/guild/upgrades/38

Now refresh that in your browser a few times with CTRL+F5. You will see, that the prerequisites change without reason! Very visible on the first entry, where 350 appears and disappears.

I spend 30mins trying to figure out why my program doesn't aggregate the data correctly for different languages...

Edit:Where it might be seen much better: Download the URL https://api.guildwars2.com/v2/guild/upgrades?ids=all several times and compare the filesizes

Edit2:Downloaded the ids=all URL 100 times with wget. I got 27 different filesizes (in byte)