My take, as someone who just read through the github issues conversation.

The model was outputting reasoning traces that were supposed to lead to tool calls. So the model might do something like:

    <think>
    I should use a tool
    </think>

    ... should make the tool call here

But a \n was slipping through from the last line of the reasoning trace so the parser was generating:

   <think>
   I should use a tool

   </think>

And that extra new line before the closing </think> would occasionally trigger the model to question itself with an "Actually ... " digression. In long running conversations this would end up looping because the "Actually ..." part would reason it should call a tool, then a new trailing \n would trigger an "Actually ..." and then it ends up in a loop.