for those who don't want to log in,
What's more interesting is later on in that thread where a support staffer noted that one of the people reporting problems was running out of memory because they'd apparently been very close to the max and that dropped slightly with the update. I had a problem with two test RDS instances suddenly failing into the invalid parameters state which turned out to be years-old config for the InnoDB pool size being just a little too large after a reboot reduced the available RAM by just enough to matter.
It's a pity, given the reasons imgur started, but it's the cycle of all image hosts I guess.
Agreed, it's a shame, but such is image hosting.