I created a post about it for discussion [0]. There is no consensus on the format and to modify the existing debugging notation. There were also suggestions to include a builtin function (dbg) like breakpoint() that does this. I guess implementation can be discussed once the idea is accepted to avoid work being wasted. It certainly can go only in 3.9 if accepted given 3.8 beta release.

[0] https://discuss.python.org/t/filename-and-line-number-in-f-string-debugging-output/1650/8