I have a 29 Jack flash with a 75 degree seat tube. I find that the comfy place is hanging off the back of my seat. Putting a longer stem on still makes the seat feel too far forward.
All my other bikes are old and I can get my saddle where I like it.
My next newest bike is a Whippet with a 73.5 seat tube , that too is fine.
Are the numbers on the flash extreme? The seat tube certainly looks very upright.

Is the top tube length the same on those bikes?

You are just used to the older, slightly slacker seat tube angles. Nothing wrong with c73deg seat tubes. They were that for years and no-one complained. Shove your seat back or put a layback post on if needed.

Modern geometry generally steepens the seat tube but lengthens the reach so the bar to saddle distance is roughly the same.