@Pesala Usually, a bug occurs unexpectedly as a consequence of something else.
A poor choice or a badly considered ux element is not a bug. I can argue that I never have more than three tabs open, so it wasn't a problem (I don't, by the way).
So this sounds to me like someone realized this behavior, the '+' being unreachable if you have too many tabs open, and put it back at the end of the bar. Problem solved right? Not quite, and here we are!
The new tab "+" should be after the last tab on the bar, and when you saturate the bar with tabs, it stays at the end of the bar.
OR, give the users the options: a) sticky b) before c) after Done!