Restore edit message history in ChatGPT

Viewing different message versions is no longer available. The UI to flip between <1/2> <2,2> has disappeared. Editing now overwrites all messages, and all threads in my previous conversations are now gone. I use this feature a lot, and often go back to previous versions of a message to compare the results. This new change is very disruptive and inconvenient. Please restore message version arrows.