Gigantify Overrides Emote URL Cache
If you use the new Gigantify power-up in chat, the emote you Gigantify will permanently load the 3x URL in chat, shrunk down to 1x size. This can cause issues for emotes that have variations depending on size, or for pixel-perfect emotes (sprites) in multiple situations.
Oddly, if the chat is not visible (in a background tab for some period of time [idle?]) at the time the gigantified emote is posted, any of the same emote posted while still not visible may use the expected size, rather than the 3x. I'm not entirely sure on the trigger conditions.
Refreshing the chat resets this (because gigantified emotes aren't shown in historical chat, I assume) until the next time the emote is gigantified.