What do you mean by "jumpy"?
When using the chat in popup mode or visible on all pages, sending text will make the keyboard disappear, pushing the bottom of the chat down to the bottom of your device, and then the keyboard will reappear and push the chat up again. Also it seems that the chat text sticks, so when new messages come in they are cut off and you have to scroll to view them.
Additionally when viewing the chat page, tapping the text input area forces the page to scroll down (i have the sidebar enabled so the effect may be less intense without it?).
Hope I explained things clearly
The way the chat jumps around is frustrating to the viewer and those who struggle with anxiety, epilepsy or eye strain can find the jumpiness overwhelming. I personally am using a Samsung Galaxy 9 phone and this is the result I get using Chrome.
Also it would be amazing if alerts for chat reactions could be a choice the user can make. Our users tend to use the react feature a lot so getting a lot of reaction notifications while you are currently in chat and can already see the reactions you're getting has been reported to be a bit annoying.