Type something in chat, then go mine some trees or something. The chat moves up to make room for the mining progress bar, then back down when you finish mining it. If you mine a bunch of entities one after the other, the chat ends up bouncing quite a bit.
I feel like the chat should reserve some space for the progress bars that may appear.
[1.1.0] Bouncy chat
Re: [1.1.0] Bouncy chat
I think this is the same bug as viewtopic.php?f=7&t=91670