G71.1 and G70 issues in 2.9.2

The reason G70 gives you a different path is because G71.1 does not cut pockets while G70 does. So in essence G70 actually cuts the path in the subroutine.

If you add a G71.2 to your program:
You can see the actual profile the subroutine creates.

 

maybe try this:

would give you:

 

A semicolon ;  tells the interpreter to ignore everything after it on that line (ie its a comment)
So if you delete this line there will be no change in the toolpath at all. I only left that in so you can still see the original line of code.

As for the arc move:
You're telling the controller to find a counter clock wise arc with radius (r.1875) from point (X 0.25 Z1.5), which is the endpoint of your G1 move, to point (x.3750 z1.1768), which is the endpoint of your G2 move. The only way to do this is the arc you see in your original post that cuts a pocket. If you want to avoid cutting a pocket with an arc of the given radius you need to move the endpoint of your G1 move closer to the end point of the arc.
The point I chose (X 0.25 Z1.28) is the other intersection of your G1 move with the arc of your original code since I thought that the geometry might be important to you, but other points are also possible of course. Often we would want the arc to be tangential on the final geometry.

This comes down to how Gcode works, no matter whether it's on a lathe or a mill.
linuxcnc.org/docs/html/gcode/g-code.html