Redefine Sketch Plane - why does the sketch get "fixed"?

[ProductDesignOnline]

Sometimes when I redefine a sketch plane the sketch geometry becomes "fixed" (green lines). Is there a specific reason why this would happen on some files/sketches but not all of them?

Here's a link to the file - https://a360.co/2Uod2fY

The sketch becomes fixed after redefining the sketch plane second sketch plane after deleting the third extrude command.

[drew.porter]

This burns me often. Coming from SolidWorks, I am accustomed to projections actually being connected to the selected geometry. Projections actually update, and when they can't, an error is shown. The workaround of always needing an offset plane is cumbersome...........