Have a vague memory, as often, about when working with tempo track that I had this otherwise too.
I remember Reaper had it by default, so maybe memory fails me and I mix that up.
Am I wrong in this - or is it only Time Warp that do this, having that active?
Think it is a very nice way to have that guide, without needing have tempo track visible.
You get a little blob as marker and tempo written right there.